TWI807393B - Processed product and process product manufacturing method - Google Patents

Abstract

The invention provides a processed product, which is a plated steel plate with a plated layer on the surface as a blank and has a cut end on the hollow cylindrical side wall; the cut end is flush with the outer surface of the side wall of the processed product, and has a sheared surface and a fractured surface, or has a sheared surface in order in the thickness direction of the cut end; and the ratio L/t1 of the remaining length L of the plating component covered by the plated layer on the surface of the cut surface to the thickness t1 of the cut end of the processed product is 0. 70 or more.

Description

Processed product and process product manufacturing method

The present invention relates to a processed product and a method for manufacturing the processed product. The processed product uses a plated steel plate with a plated layer on its surface as a blank and has a cut end.

In recent years, the use of plated steel sheets with a plated layer on the surface as raw materials for machine parts such as automobiles and home appliances has gradually increased. By using a plated steel sheet as a blank, surface treatment after forming a processed product can be omitted, and manufacturing cost can be suppressed. Also, by omitting the surface treatment after forming, it is possible to avoid the deterioration of the dimensional accuracy of the parts caused by the surface treatment after forming. The point of omitting surface treatment after molding has been studied especially for parts requiring high dimensional accuracy, such as motor housings.

When the surface treatment after forming is omitted, there will be an area where the original steel plate is exposed at the cut end of the processed product. Depending on the environment of the processed product, red rust may occur in the area where the original steel plate is exposed. Red rust will deteriorate the appearance of processed products. In addition, as time passes, the area where red rust occurs expands, so there is also a possibility that the strength of processed products will decrease due to red rust. Especially in the case of home appliances, there is also the possibility of electrical short circuits due to rust falling off.

In addition, among motor housings and the like, there are products having a shape without a flange. The above-mentioned motor case is used by inserting the motor through the opening of the motor case, and sealing the opening with another part called a bottom plate. If moisture intrudes into the motor case, it will cause motor failure or performance degradation. Therefore, high airtightness must be provided between the opening and the bottom plate. In order to ensure high airtightness, the opening must have a predetermined flat portion.

As a method of improving the antirust ability of the cut end of the processed product, for example, Patent Document 1 proposes a method of punching a Zn-based plated steel sheet with a thickness of 2 mm or less using a die having a radius of curvature of 0.1 to 0.5 times the thickness of the Zn-based plated steel sheet on the shoulder of a punch or a die, whereby the sheared surface ratio of the punched end surface after punching is 90% or more, and the zinc coating rate of the sheared surface is 50% or more.

Also, Patent Document 2 proposes a method of cutting a Zn-based plated steel sheet using a die to obtain a processed product. Regardless of the thickness of the Zn-based plated steel sheet, the die sets the punching clearance to 1 to 20% of the sheet thickness, and the shoulder of the punch or die has a radius of curvature greater than 0.12 times the thickness of the Zn-based plated steel sheet. By cutting the Zn-based plated steel sheet using the die, the sag Z of the cut end surface is obtained. Above and the sagging X is more than 0.45×plate thickness processed products.

In addition, Patent Document 3 proposes a method of half-cutting a plated steel sheet to 60 to 95% of the plate thickness under negative clearance, and shearing from the opposite side of the half-cut by flat pressing to obtain a product with end surface corrosion resistance.

In addition, Patent Document 4 discloses a method of pressing a sheet metal. The method includes: a first step, using the first punch and a first die to make a shaving allowance on the final processed surface of the punched part of the metal sheet, so as to perform a half-cutting process on the metal sheet; More than 70% of the sheared surface. prior art literature patent documents

Patent Document 1: Japanese Patent No. 5272518 Patent Document 2: Japanese Patent No. 6073025 Patent Document 3: Japanese Patent Laid-Open No. 2002-321021 Patent Document 4: Japanese Patent Laid-Open No. 2004-174542

The problem to be solved by the invention However, the method described in the above-mentioned Patent Document 1 is aimed at steel sheets with a thickness of 2 mm or less. When a steel sheet with a thickness of more than 2 mm is used as a blank, the zinc coverage of the sheared surface will be insufficient, and it may be difficult to suppress the generation of red rust. Furthermore, it is also difficult to apply to a drawn-worked product such as a motor case that thickens the flange end.

In the method described in the above-mentioned Patent Document 2, the punching clearance is set to be a positive clearance, so a fracture surface larger than 0.5 mm is likely to occur in the later stage of cutting. Also, since it is set to a positive clearance, the surface pressure between the die and the surface of the plating layer will not become high, and the plating layer will break when the material is stretched, and the original steel material will easily be exposed.

In the method described in the above-mentioned Patent Document 3, the plated steel sheet is half-cut with a negative clearance, and sheared by flat pressing from the side opposite to the half-cut. Therefore, a fractured surface may be formed at the middle position in the plate thickness direction of the trimmed edge of the plated steel sheet, and whisker-like burrs may be generated during flat pressing, thereby degrading the shape quality.

The method described in the above-mentioned Patent Document 4 is a technique related to trimming, which is to make the final processed surface of the metal sheet good by forming the sheared surface large. Even if the metal plate with the plated layer on the surface is trimmed by the method described in Patent Document 4, almost no plated layer remains on the finished surface, so the corrosion resistance of the finished surface is low.

Therefore, the present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a processed product and a method for manufacturing the processed product, which have good corrosion resistance and shape quality even when a plated steel sheet having a plate thickness of more than 2.0 mm is used as a blank.

means to solve problems In order to solve the above-mentioned problems, according to one aspect of the present invention, a processed product can be provided. The processed product is a plated steel plate with a plated layer on the surface as a blank, and has a cut end on the hollow cylindrical side wall. The ratio L/t1 of thickness t1 is 0.70 or more.

The length W1 of the fractured surface in the thickness direction of the trimmed end may be greater than 0 mm and not greater than 1.0 mm.

The length W1 of the fractured surface in the thickness direction of the trimmed end may be 0.5 mm or less.

The ratio Lt/t of the length Lt of the flat surface of the end surface of the processed product perpendicular to the side wall to the thickness t of the side wall of the processed product may be 0.35 or more.

The length of the burr at the cut end can also be less than 0.2mm.

The cut end may have a shear surface, a fracture surface, and a sizing surface sequentially in the thickness direction of the cut end, or may have a shear surface and a sizing surface in sequence, and, in the thickness direction of the cut end, the length W2 of the fracture surface between the shear surface and the sizing surface is greater than 0 mm and less than 0.5 mm.

又，為了解決上述課題，根據本發明之另一觀點，可提供一種加工品製造方法，係用以製造以表面具有鍍敷層之鍍敷鋼板作為胚料且於中空筒狀之側壁具有裁切端部之加工品的方法；該方法包含以下步驟：半裁切步驟，係使用第1衝模及第1衝頭將由胚料形成之第1胚體的裁切部分沿板厚方向進行半裁切，且第1衝模與第1衝頭之餘隙係被設定成負餘隙；及，精裁切步驟，係使用第2衝模及第2衝頭從與半裁切相同方向將半裁切後之第1胚體進行精裁切，而獲得具有裁切端部之加工品，且該裁切端部係與加工品之側壁的外表面齊平；第2衝模之內徑D ₃₂設為第1衝模之內徑D ₃₁以上，並且，令第1胚體之裁切部分的板厚為t1，令半裁切步驟後之裁切部分的殘留板厚為t2，在半裁切步驟中，第1衝模及第1衝頭之餘隙C _31-41滿足下述式(a1)，第1衝模之刀刃的曲率半徑R1滿足下述式(a2)，第1衝模或第1衝頭對第1胚體之裁切部分的壓入量D滿足下述式(a3)，且第1衝模與第1衝頭在下死點之間隔C _PD滿足下述式(a4)；在精裁切步驟中，第2衝模與第2衝頭之餘隙C _32-42滿足下述式(a5)，且第2衝模之刀刃的曲率半徑R2滿足下述式(a6)。 -0.35×t1≦C _31-41 ≦-0.01 ・・・(a1) 0.10×t1≦R1≦0.50×t1 ・・・(a2) D≧0.70×t1 ・・・(a3) C _PD ≧0.20 ・・・(a4) 0.01≦C _32-42 ≦0.2×t2 ・・・(a5) 0.25≦R2≦1.50×t2 ・・・(a6) Here, the unit of C _31-41 , C _PD , C _32-42 and R2 is mm.

此外，為了解決上述課題，根據本發明之另一觀點，可提供一種加工品製造方法，係用以製造以表面具有鍍敷層之鍍敷鋼板作為胚料且於中空筒狀之側壁具有裁切端部之加工品的方法；該方法包含以下步驟：半裁切步驟，係使用第1衝模及第1衝頭將由胚料形成之第1胚體的裁切部分沿板厚方向進行半裁切，且第1衝模與第1衝頭之餘隙係被設定成負餘隙；及，精裁切步驟，係使用第2衝模及第2衝頭從與半裁切相同方向將半裁切後之第1胚體進行精裁切，而獲得具有裁切端部之加工品，且該裁切端部係與加工品之側壁的外表面齊平；第2衝模之內徑D ₃₂設為第1衝模之內徑D ₃₁以上，並且，令第1胚體之裁切部分的板厚為t1，令半裁切步驟後之裁切部分的殘留板厚為t2，在半裁切步驟中，第1衝模及第1衝頭之餘隙C _31-41滿足下述式(b1)，第1衝模之刀刃的曲率半徑R11滿足下述式(b2-1)，第1衝頭之刀刃的曲率半徑R12滿足下述式(b2-2)，第1衝模或第1衝頭對第1胚體之裁切部分的押入量D滿足下述式(b3)，且第1衝模與第1衝頭在下死點之間隔C _PD滿足下述式(b4)；在精裁切步驟中，第2衝模與第2衝頭之餘隙C _32-42滿足下述式(b5)，且第2衝模之刀刃的曲率半徑R2滿足下述式(b6)。 -0.45×t1≦C _31-41 ≦-0.10×t1 ・・・(b1) 0.10×t1≦R11≦0.65×t1 ・・・(b2-1) 0.10×t1≦R12≦0.65×t1 ・・・(b2-2) D≧0.70×t1 ・・・(b3) C _PD ≧0.20 ・・・(b4) 0.01≦C _32-42 ≦0.2×t2 ・・・(b5) 0.25≦R2≦1.50×t2 ・・・(b6) Here, the unit of C _31-41 , C _PD , C _32-42 and R2 is mm.

The method for manufacturing the above-mentioned processed product may further include a finishing step, which is to use the processed product obtained in the fine-cutting step as the second blank, and press the corner of the cut end of the second blank against the pad to obtain a processed product with a fine-pressed surface formed at the corner.

The difference D ₃₂ -D ₃₁ between the inner diameter D ₃₁ of the first die and the inner diameter D ₃₂ of the second die may be 1.00 mm or less.

In addition, the above-mentioned method of manufacturing a processed product may further include a preparatory step before the half-cutting step. The preparatory step is to form a first blank having a hollow side wall and a flange from a plate-shaped plated steel sheet.

Invention effect As described above, according to the present invention, even when a plated steel sheet having a plate thickness of more than 2.0 mm is used as a raw material, the corrosion resistance and shape quality of the resulting processed product can be improved.

form for carrying out the invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. In addition, in this specification and drawing, about the structural element which has substantially the same functional structure, the same code|symbol is attached|subjected, and repeated description is abbreviate|omitted.

[1. First Embodiment] [1-1. Processed product] First, a processed product 1 manufactured by the processed product manufacturing method according to the first embodiment of the present invention will be described based on FIG. 1 . FIG. 1 is a perspective view showing an example of a processed product 1 manufactured by a method for manufacturing a processed product according to a first embodiment of the present invention. The processed product 1 shown in FIG. 1 is a motor case made of a plated steel plate with a plated layer on its surface as a blank. The motor case shown in FIG. 1 can be formed by performing forming processing such as drawing processing on a plate-shaped plated steel sheet.

As shown in FIG. 1 , the processed product 1 of the present embodiment has a trunk portion 10 and a protrusion 11 .

The trunk portion 10 has a hollow cylindrical side wall 101 and a top wall 103 formed to cover one end of the side wall 101 . Depending on the direction in which the processed product 1 is used, the top wall 103 may also be called by other names such as the bottom wall. The XY plane cross-sectional shape of the trunk portion 10 of the processed product 1 shown in FIG. 1 is a perfect circle, but the present invention is not limited to the above example. The cross-sectional shape of the trunk portion 10 on the XY plane may be other shapes such as ellipse or polygon, for example. The trunk portion 10 has an opening on the side opposite to the top wall 103 . The motor can be inserted through the opening.

The protrusion 11 is a protrusion protruding outward from the top wall 103 in the central axis direction (Z direction) of the trunk portion 10 . In addition, the protrusion 11 does not necessarily have to be formed, and the top wall 103 may be flat.

The trunk portion 10 of the present embodiment has a cut-off end portion 13 on the outer surface of the end portion on the opening side. The cutting end 13 is formed by cutting the blank body to be processed into the processed product 1 . The trimmed end portion 13 is formed flush with the outer surface of the trunk portion 10 .

Cutting processing includes cutting, punching and drilling. Cutting is the process of cutting the cutting object along a predetermined straight line or curve. Punching is the process of punching out products from the cutting object. Opening is the process of punching out parts that are not intended to be products to obtain products with openings. The trunk portion 10 shown in FIG. 1 with the trimmed end portion 13 can be obtained from a blank body by punching.

As the plated steel sheet, plated steel sheets having various plating layers are preferably used. Various kinds of steel sheets can be used for the plated steel sheet, but it is preferable to use a Zn-based plated steel sheet. Zn-based plating includes Zn plating, Zn-Al-based alloy plating, Zn-Al-Mg-based alloy plating, and Zn-Al-Mg-Si-based alloy plating. In particular, the plated steel plate is preferably a steel plate plated with a Zn-Al-Mg alloy. Here, the alloy plating preferably contains 80 mass % or more of Zn with respect to the total molar number of plating, and preferably contains 90 mass % or more of Zn.

The raw steel plate of the plated steel plate can be freely determined, for example, it can be very low carbon steel.

The lower limit of the plating adhesion of the plated steel sheet is preferably 30g/m ² , preferably 45g/m ² . Also, the amount of plating on the plated steel sheet is preferably 450 g/m ² as the upper limit, and preferably 190 g/m ² as the upper limit. In particular, by making the plating deposition amount more than 45 g/m ² , the plated metal can easily cover the sheared surface of the trimmed end portion 13 (the sheared surface 13c in FIG. 2 ), thereby improving the corrosion resistance after trimming.

The plate thickness of the plated steel plate (the plate thickness of the original steel plate + the plated layer thickness) can be freely determined, and can be less than 2.0mm or greater than 2.0mm. The thickness of the plated steel sheet may be, for example, not less than 0.8 mm and not more than 6.0 mm, preferably not less than 2.0 mm and not more than 4.5 mm.

[1-2. Cutting end of processed product] Next, the cut end portion 13 of the processed product 1 according to the present embodiment will be described with reference to FIGS. 2 and 3 . 2 shows the cut end portion 13 in the area A of the processed product 1 in FIG. 1 , the left side is a cross-sectional view on the ZX plane including the central axis of the processed product 1, and the right side is a side view from the X direction. FIG. 3 is a detail view of the cross-sectional view on the left side of FIG. 2 . In addition, description of the plating layers 13f1 and 13f2 is omitted in FIG. 2 .

As shown in FIGS. 2 and 3 , the cut end portion 13 of the processed product 1 is formed to be flush with the outer surface of the processed product 1 , for example, the outer surface 101 a of the side wall 101 in the Z direction. In addition, the cut end portion 13 is formed along a direction T2 which is a direction parallel to the central axis of the processed product 1 and a direction (hereinafter also referred to as a “second direction”) perpendicular to the plate thickness direction (hereinafter also referred to as a “first direction”) T1 of the side wall 101 . And, for example, as shown in FIGS. 2 and 3 , the cut end portion 13 has a sheared surface 13c and a fractured surface 13d in this order in the second direction T2.

In addition, in FIG. 2 , it is exaggerated to show that there is a slightly curved surface Rd at the boundary between the outer side surface 101a and the cut end portion 13 of the processed product. However, the curved surface portion Rd does not cause a large drop in the boundary between the outer side surface 101a and the cut end portion 13, and the outer surface 101a and the cut end portion 13 can be regarded as being flush. Here, if the drop between the surface of the cut end portion 13 and the outer surface 101a of the side wall 101 is less than 0.5mm, it is judged that there is no large drop, and the outer surface 101a and the cut end portion 13 are regarded as flush. The upper limit of the drop can also be set to 0.4mm, 0.3mm, 0.2mm or 0.1mm according to requirements. Also, the plate thickness t of the processed product 1 is defined as the plate thickness of the lowermost part of the side wall 101 of the processed product 1 . That is, the thickness t of the processed product 1 is defined as the thickness of the side wall 101 immediately above the curved portion Rd of the boundary between the outer surface 101 a of the side wall 101 and the trimmed end portion 13 .

The shearing surface 13c is the surface of the embryo body of the processed product 1 after being sheared by the blade of the cutting die. The fractured surface 13d is a surface where the cracks generated in the blank from the blade of the cutting die intersect and fracture. The fractured surface 13d is adjacent to the sheared surface 13c in the second direction T2. Also, burrs may be generated on the lower side of the fractured surface 13d (that is, on the side opposite to the sheared surface 13c). The burr is the part of the embryo body that is elongated or torn off when the fracture surface 13d is formed.

As shown in FIG. 3, in the processed product 1 produced by the processed product manufacturing method of this embodiment, a part of the sheared surface 13c of the cut end portion 13 is covered with a plated layer 13f1. The plating layer 13f1 is stretched by the cutting die to cover the shearing surface 13c when the blade of the cutting die gradually cuts into the blank body. By covering with the plating layer 13f1, at least a part of the sheared surface 13c is covered with the plating layer 13f1. On the other hand, generation of red rust can be suppressed in the portion of the sheared surface 13c coated with the plating layer 13f1. Furthermore, when the plating layer 13f1 is a Zn-based plating layer, the sacrificial anti-corrosion effect of the Zn-based plating layer can suppress the occurrence of red rust even in the vicinity of the portion coated with the plating layer 13f1. In addition, the processed product 1 shown in FIG. 3 is a processed product 1 with almost no step between the outer surface 101a and the cut end portion 13, so the illustration of the curved portion Rd is omitted in FIG. 3 .

At this time, in the processed product 1, the length L of the plating layer 13f1 covering at least a part of the cut surface 13c of the trimmed edge 13 is 0.70 times or more the thickness t1 of the trimmed edge 13 of the processed product 1 (hereinafter also referred to as "the length t1 of the trimmed edge 13"). That is, the ratio L/t1 of the plating component remaining length L covered by the plating layer 13f1 on the sheared surface 13c to the plate thickness t1 of the cut end portion 13 of the processed product 1 is 0.70 or more. The larger the ratio L/t1, the better. In addition, the lower limit of the ratio L/t1 may be set to 0.75, 0.78, 0.81, 0.83, 0.85 or 0.88. The upper limit of the ratio L/t1 is 1.00. Also, as shown in FIG. 2, the thickness t1 of the cut end portion 13 is the length along the second direction T2 from the lower end of the curved surface Rd to the end surface of the trunk portion 10 (end surface 14a in FIG. 3).

The fractured surface 13d is a surface formed as a result of intersection of cracks generated in the embryo body, and is a rough primary surface. Metal components of the steel raw material are exposed in the fractured surface 13d. It is difficult for the plated layer 13f1 covering the sheared surface 13c to cover the fractured surface 13d. Therefore, the fractured surface 13d is more likely to generate red rust earlier than other surfaces of the cut end portion 13 .

The inventors of the present invention conducted experiments by varying the plate thickness t1 of the trimmed end portion 13 of the processed product 1, trimming conditions, and surface treatment conditions in various ranges, and investigated the occurrence of red rust. The thickness t1 of the trimmed end portion 13 of the processed product 1 is changed by changing the thickness of the flange portion 20 (that is, the thickness of the plated steel sheet) shown on the left side of FIG. 5 described later. As a result, it is thought that when the plated steel sheet is cut, the plated layer 13f1 can cover the cut surface 13c to obtain the processed product 1 with a ratio L/t1 of 0.70 or more. And it was found that by this, the occurrence of red rust in the trimmed end portion 13 can be suppressed as time passes after the trimming process.

In addition, the length W1 of the fracture surface 13d (hereinafter also referred to as "fracture surface length") in the plate thickness direction (that is, the second direction T2) of the trimmed end portion 13 of the processed product 1 may be greater than 0 mm and less than or equal to 1.0 mm. If the length W1 of the fractured surface of the processed product 1 is set to be 1.0 mm or less, even if red rust occurs on the fractured surface 13d, it is not conspicuous, and thus it can be judged that it does not pose a practical problem. The fracture surface length W1 of the processed product 1 is preferably as small as possible, and may be 0.8 mm or less or 0.6 mm or less. It is more preferable to set the fracture surface length W1 of the processed product 1 to 0.5 mm or less, 0.3 mm or less, or 0.2 mm or less. Also, the ratio W1/t1 of the fracture surface length W1 to the plate thickness t1 of the trimmed end portion 13 of the processed product 1 may be less than 0.15, less than 0.10, less than 0.08, less than 0.06, or less than 0.04. Furthermore, the fracture surface length W1 of the processed product 1 may be 0 mm. That is, the cut end portion 13 of the processed product 1 may not have the fracture surface 13d. In this case, the cut end portion 13 has only the cut surface 13c in the second direction T2.

Moreover, the end surface 14a of the opening part (opening part 14 of FIG. 4) of the processed product 1 of this embodiment has the flat surface 13k. In a product without a flange as shown in FIG. 1, the end surface 14a of the trunk portion 10 will generally be a mounting surface with other parts. For example, in the case of the motor housing shown in FIG. 1, the bottom plate 15 is fixed to the end surface 14a of the trunk portion 10 as shown in FIG. 4 to seal the opening. At this time, the larger the length Lt of the flat surface 13k of the end surface 14a of the trunk portion 10, the larger the contact area with the mounting surface 15a of the bottom plate 15, and the airtightness can be improved. In order to obtain the above effects, the ratio Lt/t of the length Lt of the flat surface 13k to the plate thickness t of the side wall 101 of the processed product 1 may be 0.35 or more, 0.40 or more, or 0.50 or more, and preferably 0.60 or more, 0.70 or more, 0.80 or more, or 0.85 or more.

In addition, the length of the burrs generated on the lower side of the fractured surface 13d of the cut end portion 13 of the processed product 1 can also be set to be less than 0.2 mm. Burrs can be the cause of dents, electrical shorts, etc. By setting the length of the burrs to less than 0.2 mm, the processed product 1 has as few burrs as possible, and the occurrence of dents, electrical shorts, and the like can be suppressed. The burr length is preferably less than 0.1 mm.

The processed product of this embodiment is not cut in one step, but is produced by cutting the plated steel sheet in two steps of a half-cutting step and a fine-cutting step. Thereby, the processed product 1 which covered the sheared surface 13c with more plated layer 13f1 can be obtained. Hereinafter, the method of manufacturing a processed product according to this embodiment will be described.

[1-3. Processed product manufacturing method] First, a method of manufacturing a processed product according to this embodiment will be described with reference to FIG. 5 . Fig. 5 is an explanatory view showing a method of manufacturing a processed product according to the present embodiment. As shown in FIG. 5 , the method for manufacturing processed products in this embodiment includes: a preparation step, a half-cutting step, and a fine-cutting step.

The preparation step is a step of preparing the first embryo body 2 . The first blank body 2 can be obtained by performing forming processing such as drawing processing on a plate-shaped plated steel sheet. That is, the first raw body 2 uses a plated steel sheet as a raw material similarly to the processed product 1 . The first blank body 2 has a flange portion 20 at a position to be the trimmed end portion 13 shown in FIG. 1 . The flange portion 20 may be circular or non-circular in shape when viewed from above. On the other hand, the first base body 2 may have the same shape as that of the processed product 1 with respect to portions other than the flange portion 20 . Furthermore, the preparatory steps are not integral to the practice of the invention. If the embryo body processed by a certain method can be obtained through a third party, the preparation step can be omitted.

The half-cutting step is a step of half-cutting the first embryo body 2 . In the half-cutting step, half-cutting of the flange portion 20 is performed. The so-called half-cutting refers to the processing of cutting the flange portion 20 to a halfway position along the cutting direction of the flange portion 20 . In the present embodiment, the flange portion 20 is the removed portion 20a that will eventually become a non-product, and is cut at the boundary position with the portion that will become the side wall 101 of the trunk portion 10 of the processed product 1 . The cutting direction of the flange portion 20 is the plate thickness direction of the flange portion 20 .

The fine-cutting step is a step of fine-cutting the first embryo body 2 . In the finishing cutting step, the half-cut flange portion 20 is cut to be separated from the portion to be the side wall 101 of the trunk portion 10 of the processed product 1 . By cutting the flange portion 20 , the processed product 1 with the cut end portion 13 formed flush with the side wall 101 can be obtained. As shown in FIG. 3 , the end surface 14a of the opening 14 of the processed product 1 is covered with the plating layer 13f2 on the inner surface 101b side of the trunk portion 10 . And the end surface 14a of the opening part 14 of the processed product 1 is formed so that it may have the flat surface 13k.

In the half-cutting step and the fine-cutting step of the processed product manufacturing method of this embodiment, the first blank body 2 is processed using a die and a punch. Hereinafter, for the details of the half-cutting step and the fine-cutting step, two forms depending on the blade shape of the die and punch used in the half-cutting step will be described. The blades of dies and punches are sometimes called the "shoulder". In addition, in the following description, regarding the mold used to obtain the processed product 1 , for convenience, the upper mold (upper mold) is called a die and the lower mold (lower mold) is called a punch. Therefore, of course, this technique is also applicable to the case where the upper die (upper die) is called a punch and the lower die (lower die) is called a die. In addition, the moving direction of the die and the punch is determined according to the installation state, and may move in the vertical direction, and may also move in the horizontal direction.

(a. When only the blade of the die used in the half-cutting step is R-shaped) First, the half-cutting step and the fine-cutting step when only the blade of the die used in the half-cutting step is made into an R shape will be described with reference to FIGS. 6 and 7 . Fig. 6 is an explanatory diagram showing a half-cutting step when the blade of a die used in the half-cutting step is made into an R shape. FIG. 7 is an explanatory view showing a fine cutting step followed by the half cutting step in FIG. 6 .

(half cut step) As shown in FIG. 6 , in the half-cutting step, the flange portion 20 of the first blank body 2 is half-cut using the first die 31 and the first punch 41 . In FIG. 6 , as an aspect of half-cutting, the flange portion 20 is half-cut from the first blank body 2, which is clamped by the first punch 41 and the first guide member 51 to become the part of the side wall 101 of the trunk portion 10. The first die 31 constitutes a cutting die that is pressed into the flange portion 20 during half cutting. In this embodiment, the die that presses the part that will become the end surface (end face 14a in FIG. 3 ) of the side wall 101 of the trunk portion 10 is defined as the first punch 41, and the die that presses the flange portion 20 (that is, the removed portion 20a) is defined as the first die 31.

Here, the clearance C _{31 - 41} between the first die 31 and the first punch 41 is set as a negative clearance. Clearance C _31-41 represents the gap between the first die 31 and the first punch 41, as shown in FIG. Based on the state of no clearance (that is, when C _31-41 is zero), the clearance in the state where the first die 31 and the first punch 41 are separated is called a positive clearance when viewed from the pressing direction of the first die 31 (that is, the thickness direction of the flange part 20, and the Z direction), and the clearance in a state where the first die 31 and the first punch 41 are partially overlapped is called a negative clearance. In this specification, regarding the clearance between the die and the punch, a positive value indicates a positive clearance and a negative value indicates a negative clearance.

As shown in FIG. 6, the first die 31 and the first punch 41 for half-cutting the first blank body 2 are arranged in such a way that the first die 31 and the first punch 41 are partially overlapped when viewed from the pressing direction of the first die 31. If the clearance C _31-41 is set to a positive clearance, the cracks generated by the blades of the first die 31 and the first punch 41 may intersect as in the punching process performed once, and the removed portion 20a may be completely cut off from the flange portion 20. Also, the cutting position of the flange portion 20 will be separated from the side wall 101 of the trunk portion 10, and the cutting end portion 13 will not be flush with the side wall 101, resulting in a drop on the outer surface of the processed product 1. By setting the clearance C _31-41 as a negative clearance, the flange portion 20 (that is, the removed portion 20a) can be prevented from being completely cut from the first blank body 2 in the half-cutting step, and the cut end portion 13 can be made flush with the side wall 101.

In addition, by making the clearance C _31-41 a negative clearance, a large hydrostatic stress (hydrostatic stress) is generated in the region sandwiched by the first die 31 and the first punch 41 . Therefore, in the stress generated when the first die 31 is pressed into the flange portion 20, the ratio of the tensile stress generated between the material that becomes waste after cutting (that is, the removed portion 20a) and the side wall material that becomes the side wall 101 of the trunk portion 10 is reduced. As a result, the material in contact with the front end of the blade of the first die 31 that will become waste after cutting can easily flow from the front end of the blade of the first die 31 to the side 31a side of the first die 31, thereby increasing the extent to which the plating layer 13f1 covers the sheared surface 13c. Also, as the ratio of the tensile stress decreases and the compressive stress increases, the material that would have flowed toward the waste side is pushed back toward the side wall 101 . As a result, the portion to be the end surface 14 a of the opening 14 is compressed and flattened after cutting.

As shown in the following formula (a1), the clearance C _31-41 [mm] between the first die 31 and the first punch 41 is set to be -0.01mm or less and -0.35 times or more than the plate thickness t1 [mm] of the trimmed portion of the first blank 2 (that is, the flange portion 20). The thickness t1 of the trimmed portion of the first blank body 2 (that is, the flange portion 20 ) is equal to the thickness (t1) of the trimmed end portion 13 of the processed product 1 .

-0.35×t1≦C _31-41 ≦-0.01 ・・・(a1)

If the clearance C _31-41 is less than -0.01mm, there will be no local positive clearance due to the sliding accuracy of the press machine or the center shift of the mold, etc., and the negative clearance can be maintained. As a result, cracks are not generated during half-cutting, and there is no case where a large fracture surface occurs due to full-cutting. On the other hand, if the clearance C _31-41 is more than -0.35 times the plate thickness t1 of the flange portion 20, the forming load required for half-cutting will not increase, so the pressing capacity will not be exceeded. Therefore, the load on the mold is also small, and the reduction in the life of the mold can be suppressed.

The clearance C _31-41 is more preferably -0.30 times or more, -0.25 times or more, or -0.20 times or more the plate thickness t1 of the flange portion 20 . By setting the clearance C _31-41 to -0.30 times or more, -0.25 times or more, or -0.20 times or more the thickness t1 of the flange portion 20, the width Lt of the flat surface 13k of the end surface 14a of the opening 14 after trimming can be made 0.35 times or more the thickness t of the side wall 101 of the processed product 1. The upper limit of the clearance C _31-41 may be -0.05 times, -0.10 times, or -0.15 times the plate thickness t1 of the flange part 20.

As shown in FIG. 6, the blade of the first die 31 is formed in an R shape having a curvature radius R1. Since the first die 31 is pressed into the flange portion 20 as shown in FIG. 6 , the blade of the first die 31 is formed into an R shape having a curvature radius R1.

As shown in the following formula (a2), the curvature radius R1 is not less than 0.10 times and not more than 0.50 times the plate thickness t1 [mm] of the flange portion 20 of the first blank body 2 .

0.1×t1≦R1≦0.5×t1 ・・・(a2)

If the radius of curvature R1 is more than 0.10 times the plate thickness t1, a large hydrostatic stress can be generated under the negative clearance without scraping off the plating layer 13f1, so that the waste material directly below the first die 31 flows from the blade of the first die 31 to the side surface 31a of the first die 31. This flow reduces the ratio of the tensile stress generated between the material that becomes waste after cutting (that is, the removed portion 20 a ) and the side wall material that becomes the side wall 101 of the trunk portion 10 in the stress generated when the first die 31 is pressed into the flange portion 20 . As a result, the sheared surface 13c can be covered with the plating layer 13f1. On the other hand, if the radius of curvature R1 is set to 0.50 times or less than the plate thickness t1, the material on the edge of the first die 31 during half-cutting is reduced, and the formation of the fractured surface 13d can be reduced in the subsequent fine-cutting.

Also, the blade of the first punch 41 is formed in a square shape without roundness as shown in FIG. 6 . At this time, the blade of the first punch 41 may have a radius of curvature smaller than 0.1 times the thickness t1 of the flange portion 20 of the first blank body 2 . In addition, the radius of curvature of the blade of the first punch 41 may also be set to be less than 0.06 times, less than 0.04 times or less than 0.02 times the thickness t1 of the flange portion 20 of the first blank body 2 as required.

As shown in the following formula (a3), the pressing amount D [mm] of the first die 31 pressed into the flange portion 20 of the first blank body 2 is set to 0.70 times or more than the plate thickness t1 [mm] of the trimmed portion of the first blank body 2 (that is, the flange portion 20). As shown in FIG. 6, the pushing amount D is the moving amount of the first die 31, and the moving amount is calculated from the position where the first die 31 contacts the upper surface of the flange portion 20 of the first blank body 2 to the position where the pressing of the first die 31 stops (hereinafter this position is also referred to as "bottom dead point"). In addition, as shown in the following formula (a4), the distance C _PD [mm] between the first die 31 and the first punch 41 at the bottom dead center is set to be 0.20 mm or more.

D≧0.70×t1 ・・・(a3) C _PD ≧0.20 ・・・(a4)

After half-cutting, the remaining thickness t2 of the flange portion 20 (that is, the removed portion 20 a ) remaining on the first blank body 2 may be 0.30 times or less than the thickness t1 [mm] of the flange portion 20 . Here, the remaining plate thickness t2 refers to the remaining plate thickness in the outer side surface 101 a of the side wall 101 of the processed product 1 . If the press-in amount D is more than 0.70 times the plate thickness t1, the fracture surface 13d will not be easily formed in the subsequent fine cutting. On the other hand, by ensuring that the distance C _PD between the first die 31 and the first punch 41 at the bottom dead center is 0.20 mm or more, it is possible to avoid the partial complete cutting caused by cracks during half cutting. In addition, the burden on the mold is small, and the reduction of the life of the mold can be suppressed. Also, the distance C _PD is set to be the minimum value of the distance between the first die 31 and the first punch 41 at the bottom dead center.

Furthermore, the pressing amount D of the first die 31 pressed into the flange portion 20 of the first blank body 2 may be at least 0.70 times the thickness t1 [mm] of the flange portion 20 of the first blank body 2 as shown in the above formula (a3), and may be set at 0.95 times or less (0.70×t1≦D≦0.95×t1).

As shown in the central figure of FIG. 6, the residual plate thickness t2 is the value obtained by subtracting the pressing amount D of the first die 31 into the flange portion 20 from the plate thickness t1 of the flange portion 20, and adding the radius of curvature R1 to the obtained value (t2=t1-D+R1). Therefore, the remaining plate thickness t2 is different from the distance C _PD between the bottom dead centers of the first die 31 and the first punch 41 . If the press-in amount D is more than 0.70 times the plate thickness t1, the fracture surface 13d will not be easily formed in the subsequent fine cutting. On the other hand, if the press-in amount D is less than 0.95 times the plate thickness t1, there will be no cracks in half-cutting due to the sliding accuracy of the press machine or the center shift of the mold, etc., and there will be no large fracture surface due to complete cutting. In addition, the burden on the mold is small, and the reduction of the life of the mold can be suppressed.

(fine cutting step) As shown in FIG. 7 , in the finishing cutting step, the half-cut flange portion 20 is precisely cut using the second die 32 and the second punch 42 . In FIG. 7 , as an example of fine cutting, the second punch 42 and the second guide 52 are used to clamp the part that will become the side wall 101 of the trunk part 10, and the flange part 20 (that is, the removed part 20a) is fine blanked from the first blank body 2. The second die 32 constitutes a cutting die that is pressed into the flange portion 20 during finishing cutting. In this embodiment, the die that presses the part that will become the end face (end face 14a in FIG. 3 ) of the side wall 101 of the trunk portion 10 is defined as the second punch 42, and the die that presses the flange portion 20 (that is, the removed portion 20a) is defined as the second die 32. The second die 32 may be the same as the first die 31 . That is, the first die 31 used in the half-cutting step may be used as the second die 32 in the finishing cutting step.

The positional relationship between the second die 32 and the first blank body 2 is preferably the same as the positional relationship between the first die 31 and the first blank body 2 . When the positional relationship between them is different, for example, if the diameter of the second die 32 is larger than that of the first die 31 , a drop will occur at the cutting end 13 . Conversely, for example, if the diameter of the second die 32 is smaller than that of the first die 31, the second die 32 will contact the half-cut cut end produced in the half-cut step, and the second die 32 may scrape off the plating layer 13f covering the sheared surface 13c.

The fine cutting of this embodiment is carried out from the same direction as the half cutting. That is, after pressing the first die 31 into the flange portion 20 from above the flange portion 20 in half cutting as shown in FIG. 6, as shown in FIG. Thereby, the removed portion 20a can be separated from the first embryo body 2 .

The clearance C _32-42 between the second die 32 and the second punch 42 is set to be a positive clearance. The clearance C _{32 - 42} is represented by the distance between the side surface 32 a of the second die 32 and the side surface 42 a of the second punch 42 . Here, like the half-cutting step, the clearance in the state where the second die 32 and the second punch 42 are separated is called a positive clearance, and the clearance in a state where the second die 32 and the second punch 42 are partially overlapped is called a negative clearance.

As shown in the following formula (5), the clearance C _32-42 [mm] between the second die 32 and the second punch 42 is set to be more than 0.01 mm and less than 0.2 times the remaining thickness t2, which is the thickness of the removed portion 20a remaining on the flange portion 20 of the first blank 2 after half-cutting.

0.01≦C _32-42 ≦0.2×t2・・・(5)

If the clearance C _32-42 is 0.01 mm or more, the blade of the second die 32 and the blade of the second punch 42 will not come into contact even if the sliding accuracy of the pressing machine or the center shift of the mold occurs during fine cutting. On the other hand, if the clearance _C32-42 is 0.2 times or less of the remaining plate thickness t2, burrs are less likely to be generated at the tip of the fractured surface 13d. The lower limit of the clearance C _32-42 can also be set as 0.05 times or 0.10 times of the remaining plate thickness t2.

The blade of the second die 32 has an R shape having a curvature radius R2. Since the second die 32 is pressed into the portion of the flange portion 20 to be trimmed as shown in FIG. 7 , the blade of the second die 32 is formed into an R shape having a radius of curvature R2. Also, the blade of the second punch 42 is formed in a square shape without roundness as shown in FIG. 7 . In this case, the blade of the second punch 42 may have a radius of curvature smaller than 0.25 mm, smaller than 0.15 mm, smaller than 0.10 mm, or smaller than 0.05 mm. Alternatively, the radius of curvature of the blade of the second punch 42 can also be set to be less than 0.1 times the thickness t1 of the flange portion 20 of the first blank body 2, and can also be set to be less than 0.06 times, less than 0.04 times or less than 0.02 times as required.

As shown in the following formula (6), the radius of curvature R2 [mm] is 0.25 mm or more and 1.50 times or less of the remaining plate thickness t2 of the half-cut part.

0.25≦R2≦1.50×t2 ・・・(6)

If the radius of curvature R2 is 0.25 mm or more, the second die 32 will not scrape off the plating layer 13f1 covering the sheared surface 13c. On the other hand, if the radius of curvature R2 is 1.50 times or less the remaining plate thickness t2, burrs are less likely to be generated at the tip of the fractured surface 13d.

In addition, the inner diameter D ₃₂ of the second die 32 is made the same as or slightly larger than the inner diameter D ₃₁ of the first die 31 . Specifically, the difference D 32 _-D 31 between the inner diameter D ₃₁ of the first die 31 and the inner diameter D ₃₂ of the second die ₃₂ is preferably 1.00 mm or less. Thereby, the drop can be reduced to obtain a good cut section. The drop is caused by the inner diameter difference _D32 -D31 of the dies 31 and ₃₂ at the cut end 13 of the processed product 1 due to the two steps of the half-cut step and the fine-cut step. In addition, in terms of the quality of the processed product 1, when the drop of the cut end 13 is allowable, the inner diameter difference D ₃₂ -D ₃₁ can be greater than 1.00 mm. The upper limit of the inner diameter difference D ₃₂ -D ₃₁ is as small as possible, and can also be set to 0.75mm, 0.50mm, 0.35mm or 0.20mm. Also, the lower limit of the inner diameter difference D ₃₂ -D ₃₁ is 0 mm.

(b. When the blades of dies and punches used in the half-cutting step are R-shaped) Next, the half-cutting step and the fine-cutting step when the blades of the punches and punches used in the half-cutting step are R-shaped will be described with reference to FIGS. 8 and 9 . Fig. 8 is an explanatory view showing the half-cutting step when the blades of the die and the punch used in the half-cutting step are made into an R shape. FIG. 9 is an explanatory diagram showing a fine cutting step followed by the half cutting step in FIG. 8 .

(half cut step) As shown in FIG. 8 , in the half-cutting step, the flange portion 20 of the first blank body 2 is half-cut using the first die 31 and the first punch 41 . In Fig. 8, as a state of half-cutting, the state of half-cutting the flange portion 20 from the first blank body 2 is shown in the same manner as in Fig. 6. The first blank body 2 is clamped by the first punch 41 and the first guide member 51 to become the part of the side wall 101 of the trunk portion 10. The first die 31 constitutes a cutting die that is pressed into the flange portion 20 during half cutting. In this embodiment, the die that presses the part that will become the end surface (end face 14a in FIG. 3 ) of the side wall 101 of the trunk portion 10 is defined as the first punch 41, and the die that presses the flange portion 20 (that is, the removed portion 20a) is defined as the first die 31.

The clearance C _31-41 between the first die 31 and the first punch 41 is a negative clearance. Therefore, as shown in FIG. 8, the first die 31 and the first punch 41 for half-cutting the first blank body 2 are arranged in such a way that the first die 31 and the first punch 41 are partially overlapped when viewed from the pressing direction of the first die 31. By setting the clearance C _31-41 as a negative clearance, the flange portion 20 (that is, the removed portion 20a) can be prevented from being completely cut from the first blank body 2 in the half-cutting step, and the cut end portion 13 can be made flush with the side wall 101. Also, the meanings of clearance C _31-41 , negative clearance, and positive clearance in this form b are the same as in the above-mentioned form a.

In addition, by setting the clearance C _31-41 as a negative clearance, a large hydrostatic stress is generated in the region sandwiched by the first die 31 and the first punch 41 . Therefore, in the stress generated when the first die 31 is pressed into the flange portion 20, the ratio of the tensile stress generated between the material that becomes waste after cutting (that is, the removed portion 20a) and the side wall material that becomes the side wall 101 of the trunk portion 10 is reduced. As a result, the material in contact with the front end of the blade of the first die 31 that will become waste after cutting can easily flow from the front end of the blade of the first die 31 to the side 31a side of the first die 31, thereby increasing the extent to which the plating layer 13f1 covers the sheared surface 13c. Also, as the ratio of the tensile stress decreases and the compressive stress increases, the material that would have flowed toward the waste side is pushed back toward the side wall 101 . As a result, the portion to be the end surface 14 a of the opening 14 is compressed and flattened after cutting.

As shown in the following formula (b1), the clearance C _31-41 [mm] between the first die 31 and the first punch 41 is set to -0.10 times or less and -0.45 times or more of the plate thickness t1 [mm] of the trimmed part of the first blank body 2 (that is, the flange portion 20).

-0.45×t1≦C _31-41 ≦-0.10×t1・・・(b1)

If the clearance C _31-41 is -0.10 times or less than the plate thickness t1 of the flange portion 20, a large hydrostatic stress will be generated in the region sandwiched by the first die 31 and the first punch 41, and the ratio of the tensile stress will decrease. As a result, cracks are generated during the half-cutting, and the situation that a large fracture surface occurs due to the complete cutting disappears, and the flange portion 20 (that is, the removed portion 20a) can be prevented from being completely cut from the first blank body 2 in the half-cutting step. On the other hand, if the clearance C _31-41 is -0.45 or more times the plate thickness t1 of the flange portion 20, the forming load required for half-cutting will not increase and the pressing capacity will not be exceeded. Therefore, the burden on the mold is also small, and the reduction in the life of the mold can be suppressed.

The clearance C _31-41 is more preferably -0.15 times or less the plate thickness t1 of the flange portion 20 . By setting the clearance C _31-41 to -0.15 times or less or -0.20 times or less the thickness t1 of the flange portion 20, the width Lt of the flat surface 13k of the end surface 14a of the opening 14 after trimming can more reliably be 0.35 times or more the thickness t of the side wall 101 of the processed product 1. The lower limit of the clearance C _31-41 may be -0.40 times, -0.35 times, or -0.30 times the plate thickness t1 of the flange portion 20 .

As shown in FIG. 8 , in this embodiment, the blades of the first die 31 and the first punch 41 are R-shaped. As shown in the following equations (b2-1) and (b2-2), the radius of curvature R11 [mm] of the blade of the first die 31 and the radius of curvature R12 [mm] of the blade of the first punch 41 are set to be 0.10 times or more and 0.65 times or less of the plate thickness t1 [mm] of the trimmed portion of the first blank 2 (that is, the flange portion 20). Also, the radius of curvature R11 of the blade of the first die 31 and the radius of curvature R12 of the blade of the first punch 41 may be the same or different.

0.10×t1≦R11≦0.65×t1・・・(b2-1) 0.10×t1≦R12≦0.65×t1・・・(b2-2)

If the radii of curvature R11 and R12 are more than 0.10 times the plate thickness t1, a large hydrostatic stress can be generated under the negative clearance without scraping off the plating layer 13f1, so that the waste material directly under the first die 31 flows from the blade of the first die 31 to the side surface 31a of the first die 31. This flow reduces the ratio of the tensile stress generated between the material that becomes waste after cutting (that is, the removed portion 20 a ) and the side wall material that becomes the side wall 101 of the trunk portion 10 in the stress generated when the first die 31 is pressed into the flange portion 20 . As a result, the sheared surface 13c can be covered with the plating layer 13f1. On the other hand, if the radii of curvature R11 and R12 are set to be less than 0.65 times the plate thickness t1, the material on the edge of the first die 31 will be reduced during half-cutting, and the formation of the fractured surface 13d in the subsequent fine cutting can be reduced.

As shown in the following formula (b3), the pressing amount D [mm] of the first die 31 pressed into the flange portion 20 of the first blank body 2 is set to 0.70 times or more than the plate thickness t1 [mm] of the trimmed portion of the first blank body 2 (that is, the flange portion 20). The pushing amount D is the moving amount of the first punch 31, and the moving amount is calculated from the position where the first punch 31 touches the upper surface of the flange portion 20 of the first blank body 2 to the position where the pressing of the first punch 31 stops (hereinafter this position is also referred to as "bottom dead center"). As shown in the following formula (b4), the distance C _PD [mm] between the first die 31 and the first punch 41 at the bottom dead center is set to 0.20 mm or more.

D≧0.70×t1 ・・・(b3) C _PD ≧0.20 ・・・(b4)

After half-cutting, the remaining thickness t2 of the flange portion 20 (that is, the removed portion 20 a ) remaining on the first blank body 2 may be 0.30 times or less than the thickness t1 [mm] of the flange portion 20 . Here, the remaining plate thickness t2 refers to the remaining plate thickness on the outer side surface 101a of the side wall 101 of the processed product 1, and is different from the interval _CPD . If the press-fit amount D is at least 0.70 times the plate thickness t1 of the flange portion 20, the fractured surface 13d is less likely to be formed in the subsequent finishing cutting. On the other hand, by ensuring that the distance C _PD between the first die 31 and the first punch 41 at the bottom dead center is 0.20 mm or more, it is possible to avoid the partial complete cutting caused by cracks during half cutting. In addition, the burden on the mold is small, and the reduction of the life of the mold can be suppressed. Also, the distance C _PD is set to be the minimum value of the distance between the first die 31 and the first punch 41 at the bottom dead center.

Compared with the case where only one of the first die 31 and the first punch 41 has an R-shaped blade as shown in FIG. That is, compared with the case where only one of the blades of the first die 31 or the first punch 41 is R-shaped as shown in FIG.

In the case where only the blade of the first die 31 is R-shaped as in the above-mentioned form a, the blade of the first die 31 will contact the blade of the first punch 41 if the pressing amount D of the first die 31 is set to be greater than or equal to the thickness t1 of the cut portion (that is, the flange portion 20). Therefore, in the above-mentioned form a, the pressing amount D of the first die 31 cannot be set to be equal to or greater than the plate thickness t1 of the flange portion 20 . However, if the blades of the first die 31 and the first punch 41 are R-shaped, as shown in FIG. Therefore, the trimming amount of the flange portion 20 can be set larger than the trimming amount of the form a, and the ratio of the sheared surface 13c in the trimmed end portion 13 can be increased. Thereby, more plating layers 13f1 can cover the cut surface 13c, so that the ratio of the cut end portion 13 covered by the plating layer 13f1 can be increased. In addition, since the remaining plate thickness t2 becomes smaller, the trimming amount in the fine trimming step becomes smaller, and it is possible to avoid a state where there is no residual plating layer in a part of the trimmed portion.

(fine cutting step) As shown in FIG. 9 , in the finishing cutting step, the half-cut flange portion 20 is precisely cut using the second die 32 and the second punch 42 . The fine cutting step can be performed in the same manner as the fine cutting step shown in FIG. 7. The fine cutting step shown in FIG.

In FIG. 9 , as an example of fine cutting, the second punch 42 and the second guide 52 are used to clamp the part to be the side wall 101 of the trunk part 10, and the flange part 20 (that is, the removed part 20a) is fine blanked from the first blank body 2. The second die 32 constitutes a cutting die that is pressed into the flange portion 20 during finishing cutting. In this embodiment, the die that presses the part that will become the end face (end face 14a in FIG. 3 ) of the side wall 101 of the trunk portion 10 is defined as the second punch 42, and the die that presses the flange portion 20 (that is, the removed portion 20a) is defined as the second die 32. The second die 32 may be the same as the first die 31 . That is, the first die 31 used in the half-cutting step may be used as the second die 32 in the finishing cutting step.

The positional relationship between the second die 32 and the first blank body 2 is preferably the same as the positional relationship between the first die 31 and the first blank body 2 . When the positional relationship between them is different, for example, if the diameter of the second die 32 is larger than that of the first die 31 , a drop will occur at the cutting end 13 . Conversely, for example, if the diameter of the second die 32 is smaller than that of the first die 31, the second die 32 will contact the half-cut cut end produced in the half-cut step, and the second die 32 may scrape off the plating layer 13f covering the sheared surface 13c.

The fine cutting of this embodiment is carried out from the same direction as the half cutting. That is, after pressing the first die 31 into the flange portion 20 from above the flange portion 20 in half cutting as shown in FIG. 8, as shown in FIG. Thereby, the removed portion 20a can be separated from the first embryo body 2 .

The clearance C _32-42 [mm] between the second die 32 and the second punch 42 is a positive clearance. As shown in the above formula (5), the clearance C _32-42 between the second die 32 and the second punch 42 is set to be more than 0.01 mm and less than 0.2 times the remaining thickness t2, which is the thickness of the removed part 20a remaining on the first blank 2 after half-cutting. If the clearance C _32-42 is 0.01 mm or more, the blade of the second die 32 and the blade of the second punch 42 will not come into contact even if the sliding accuracy of the pressing machine or the center shift of the mold occurs during fine cutting. On the other hand, if the clearance _C32-42 is 0.2 times or less of the remaining plate thickness t2, burrs are less likely to be generated at the tip of the fractured surface 13d.

The blade of the second die 32 has an R shape having a curvature radius R2. Since the second die 32 is pressed into the portion of the flange portion 20 to be trimmed as shown in FIG. 9 , the blade of the second die 32 has an R shape having a radius of curvature R2. In addition, the blade of the second punch 42 may be a square without roundness as shown in FIG. 7, or may have a radius of curvature. If the blade of the second punch 42 is formed into a square shape without roundness, the burr generated at the tip of the fractured surface 13d can be made smaller. The radius of curvature of the blade of the second punch 42 can be set to be less than 1.00 mm, less than 0.50 mm, less than 0.20 mm, less than 0.10 mm or less than 0.05 mm. Alternatively, the radius of curvature of the blade of the second punch 42 can also be set to be less than 0.3 times the thickness t1 of the flange portion 20 of the first blank body 2, and can also be set to be less than 0.1 times, less than 0.06 times, less than 0.04 times or less than 0.02 times as required.

As shown in the above formula (6), the radius of curvature R2 [mm] is set to be 0.25 mm or more and 1.50 times or less of the remaining plate thickness t2 of the half-cut part. If the radius of curvature R2 is 0.25 mm or more, the second die 32 will not scrape off the plating layer 13f1 covering the sheared surface 13c. On the other hand, if the radius of curvature R2 is 1.50 times or less the remaining plate thickness t2, burrs are less likely to be generated at the tip of the fractured surface 13d.

In the above, the method of manufacturing a processed product according to the first embodiment of the present invention has been described. According to this embodiment, the first blank body 2 formed of a plated steel plate and having the flange portion 20 is regarded as the cutting object, and includes the following steps: a half-cutting step, using the first die 31 and the first punch 41 to half-cut the flange portion 20 of the first blank body 2, and the clearance between the first die 31 and the first punch 41 is set to a negative clearance; Cut in the same direction and finish trimming the half-cut flange portion 20 to obtain a processed product 1 with a trimmed end portion 13 flush with the side wall 101 of the trunk portion 10 .

In the processed product 1 that has been cut in two steps as described above, the cut end portion 13 has a sheared surface 13c and a fractured surface 13d sequentially in the thickness direction of the cut portion. At least a part of the sheared surface 13c is covered with the plating layer 13f1. At this time, the ratio L/t1 of the plating component remaining length L covered by the plating layer 13f1 on the sheared surface 13c to the plate thickness t1 of the cut end portion 13 of the processed product 1 is 0.70 or more. As mentioned above, in the processed product 1, many plated layers 13f1 cover the sheared surface 13c. Even in the case of using a plated steel sheet with a thickness of more than 2.0 mm as the blank, the corrosion resistance and shape quality can still be improved.

In addition, in the method for manufacturing a processed product of this embodiment, at least the blade of the die is R-shaped for the dies used in the half-cutting step and the finishing cutting step. Thereby, there is no need to provide a gap between the trunk portion 10 of the processed product 1 and the die that is pressed into the cut portion. As a result, a processed product 1 having the trimmed end portion 13 flush with the trunk portion 10 without a step on the outer surface of the processed product 1 can be obtained. When the blade of the punching die is also sharp, the punching die belonging to the knife is set away from the trunk portion 10 in a manner that does not contact the trunk portion 10 . The reason is that the plating layer 13f1 on the surface of the trunk part 10 will be scraped off if the die pressed into the cut part comes into contact with the trunk part 10 . If the punching die is set away from the trunk portion 10 in the above-mentioned manner, after the flange portion 20 is cut, the outer surface of the processed product 1 will have a drop. Since according to the processed product manufacturing method of this embodiment, there is no need to provide a gap between the trunk portion 10 of the processed product 1 and the die that is pressed into the cut portion, the processed product 1 having the cut end portion 13 flush with the trunk portion 10 can be obtained.

In addition, according to the processed product manufacturing method of this embodiment, the end surface 14a of the opening 14 of the processed product 1 can be flattened. In the processed product manufacturing method of this embodiment, the gap C _31-41 between the die and the punch in the half-cutting step is set as a negative clearance, so that a large hydrostatic stress will be generated in the area enclosed by the first die 31 and the first punch 41. Thereby, the part which becomes the end surface 14a of the opening part 14 after a cutting process is compressed, and the large flat surface 13k can be formed. In a product without a flange as shown in FIG. 1, the end surface 14a of the trunk portion 10 will generally be a mounting surface with other parts. Since the larger flat surface 13k can be formed, when it is mounted on other parts, the contact area between the mounting surface of other parts and the end face of the trunk portion 10 can be increased, and the airtightness can be improved.

Furthermore, the cut surface 13c can be covered with more plated layers 13f by the method of manufacturing a processed product of this embodiment, so red rusting of the cut end portion 13 that occurs with time after cutting can be suppressed.

In addition, the clearance C _32-42 between the second die 32 and the second punch 42 is set to be 0.01 mm or more, and the portion left after half-cutting is 0.2 times or less the remaining plate thickness t2 of the first blank 2 . This prevents the blade of the second die 32 from being damaged due to contact with the blade of the second punch 42 during finishing cutting, and suppresses the generation of burrs.

Also, the tip of the blade of the second die 32 to be pressed into the portion of the first blank 2 that is the subject of fine trimming is provided with a curved shape having a radius of curvature R2 of not less than 0.25 mm and not more than 1.50 times the remaining plate thickness t2 of the portion after half-cutting. Thereby, the cutting die can prevent the plating layer 13f1 covering the shearing surface 13c from being scraped off, and the generation of burrs can be suppressed.

[2. Second Embodiment] Next, a method for manufacturing a processed product according to a second embodiment of the present invention will be described with reference to FIG. 10 . Fig. 10 is an explanatory view showing a method of manufacturing a processed product according to a second embodiment of the present invention. As shown in FIG. 10 , the manufacturing method of the processed product in this embodiment includes: a preparation step, a half-cutting step, a fine-cutting step and a fine-pressing step.

The method of manufacturing a processed product of this embodiment is a method in which a sizing step is added to the method of manufacturing a processed product of the first embodiment shown in FIG. 6 . As shown in FIG. 10, also in this embodiment, the half-cutting step and the fine-cutting step are performed on the first green body 2 prepared in the preparation step in the same manner as in the first embodiment. Therefore, detailed description of the preparation step, half-cutting step, and fine-cutting step is omitted.

The sizing step is to use the processed product obtained in the sizing and cutting step as the 2nd green body 6, and carry out the sizing process on the 2nd green body 6. In the sizing step, after the sizing step, the corner 13g of the cut end 13 on the fractured surface 13d side is pressed against the sizing lower die (the sizing lower die 7 in FIG. 11 ) to obtain the processed product 1 having a sizing surface 13h formed at the corner. By sizing, the region of the fractured surface 13d of the rough primary surface can be reduced, and the region where red rust occurs can be suppressed. In addition, the burrs can be flattened by sizing, and it is possible to more reliably suppress the burrs from remaining in the processed product 1 .

The sizing step will be described in more detail with reference to FIGS. 11 to 14 . Fig. 11 is a schematic view showing an example of a mold used for coining. FIG. 12 is a partially enlarged view of area B in FIG. 11 . 13 shows the cut end of the processed product 1 after the sizing step, the left side is a cross-sectional view on the ZX plane including the central axis of the processed product 1, and the right side is a side view from the X direction. Fig. 14 is a photograph showing an example of the trimmed end of the processed product 1 after the sizing step.

In addition, in FIG. 13, description of the plating layers 13f1 and 13f2 is omitted similarly to FIG. 2 . In addition, in FIG. 13 , it is exaggerated to show that there is a slightly curved surface Rd at the boundary between the outer side surface 101a and the cut end portion 13 of the processed product. However, the curved surface portion Rd does not cause a drop in the boundary between the outer side surface 101a and the cut end portion 13, and the outer surface 101a and the cut end portion 13 can be considered to be flush. In addition, the cut end portion 13 of the processed product 1 shown in FIG. 14 is not flush with the outer surface of the trunk portion 10, but is the cut end portion of a processed product having a flange portion on the outer periphery of the trunk portion 10, and is located at the front end of the flange portion. Although the processed product shown in FIG. 14 is different from the processed product 1 of this embodiment, the appearance of the sheared surface 13c, fractured surface 13d, and sizing surface 13h of the processed product 1 of this embodiment is the same as that of FIG. 14 .

In the sizing step of this embodiment, for example, as shown in FIG. 11, the sizing lower die 7 and the sizing upper die 8 are used to process the second green body 6. The sizing lower die 7 and the sizing upper die 8 are formed with recesses corresponding to the shape of the second blank body 6 . The coining lower mold 7 is for accommodating the opening 14 side of the second embryo body 6, and the coining upper mold 8 is for accommodating the protrusion 11 side of the second embryo body 6. In the coining process, the second blank body 6 is sandwiched between the coining lower die 7 and the coining upper die 8, and the corner 13g of the cut end portion 13 of the second blank body 6 is pressed against the pressing surface of the coining lower die 7 (pressing surface 72 in FIG. 12 ), thereby forming a coining surface at the cutting end portion 13. And, the cut end portion 13 of the processed product 1 after the sizing step is, for example, as shown in the photograph of FIG. 14 .

In more detail, as shown in FIG. 12 , the lower sizing die 7 has: a vertical wall surface 70 , a bottom wall surface 71 and a pressing surface 72 .

The vertical wall surface 70 is arranged so that when the trimming end 13 of the second blank body 6 is clamped by the sizing lower mold 7 and the sizing upper mold 8 , it will face the shearing surface 13c of the second blank body 6 and be approximately parallel. And the vertical wall surface 70 is arrange|positioned parallel to the advancing and retreating direction (Z direction in FIG. 12) of the sizing upper die 8. As shown in FIG.

The bottom wall surface 71 is disposed so as to sandwich the second blank body 6 so as to face the end surface 14a. Furthermore, the bottom wall surface 71 extends in a direction perpendicular to the vertical wall surface 70 .

The pressing surface 72 is a surface connecting the bottom wall surface 71 and the bottom wall surface 71 . The pressing surface 72 is provided for forming a sizing surface (the sizing surface 13h in FIG. 13 ) on the second blank body 6 . Also, the pressing surface 72 is formed in a shape corresponding to the shape of the coining surface. For example, as shown in FIG. 13, when the sizing surface 13h is to be a planar chamfered surface (hereinafter referred to as "C surface"), it is only necessary to make the pressing surface 72 an inclined plane with respect to the vertical wall surface 70 and the bottom wall surface 71. Also, for example, when the sizing surface 13h is to be curved (either the pressing surface or the compressing surface; hereinafter referred to as "R surface"), the pressing surface 72 may be curved.

In the coining step, as shown in FIG. 12 , in a state where the trimmed end portion 13 of the second blank body 6 is opposed to the vertical wall surface 70 of the lower coining die 7 , the upper coining die 8 is pressed toward the lower coining die 7 , and the second green body 6 is sandwiched between the upper coining die 8 and the bottom wall surface 71 of the lower coining die 7 . Then, press the sizing upper mold 8 toward the bottom wall surface 71, so that the second blank body 6 is pressed down until the end surface 14a of the second blank body 6 contacts the bottom wall surface 71. Here, the corner portion 13g is pressed against the pressing surface 72 before the end surface 14a of the second blank body 6 contacts the bottom wall surface 71 . After the corner portion 13g is pressed against the pressing surface 72, the sizing upper mold 8 is further pressed in so that the end surface 14a of the second blank body 6 contacts the bottom wall surface 71. The corner portion 13g is crushed by the pressing surface 72 to form a sizing surface 13h.

The fine-pressed surface 13h is a smooth surface transferred from the surface of the pressing surface 72, and is less prone to red rust than the rough fractured surface 13d. The reason for this is presumed to be that moisture is less likely to stay on the sizing surface 13h because the surface roughness becomes smooth. In addition, it is presumed that the fact that the plated layer 13f2 continuously covering the end surface 14a from the inner surface side of the second blank body 6 is stretched thinly onto the sizing surface 13h is also a factor that prevents red rust from occurring. By forming the sizing surface 13h at the corner 13g, the fracture surface length W2 (see FIG. 13 ) of the trimmed end portion 13 after sizing becomes shorter than the fractured surface length W1 (see FIGS. 2 and 3 ) of the trimmed end portion 13 before sizing. That is, the region of the fractured surface 13d which is the rough primary surface can be reduced by sizing, and the region where red rust occurs can be suppressed. In addition, since the burrs generated at the corners 13g can be flattened by sizing, the remaining burrs in the processed product 1 can be reduced to less than 0.2mm, and the remaining burrs can be more reliably suppressed. The length of the flash is preferably less than 0.1 mm, and preferably less than 0.05 mm or less than 0.01 mm.

In the sizing step, the pressing surface 72 is pressed against the corner 13g so that the length (fracture surface length) W2 of the fractured surface 13d between the sheared surface 13c and the sizing surface 13h of the processed product 1 becomes greater than 0mm and 0.5mm or less. By setting the fracture surface length W2 to be greater than 0 mm and not more than 0.5 mm, even if red rust occurs on the fracture surface 13d, it is not conspicuous, so it can be judged that there is no practical problem.

Furthermore, in the precision cutting step, it is preferable to obtain the second green body 6 whose fracture surface length W1 is less than 1.0 mm. By obtaining the second green body 6 whose fracture surface length W1 is less than 1.0 mm, the fracture surface length W2 can be more reliably set to 0.5 mm or less in the sizing step. The fracture surface length W2 of the processed product 1 is preferably as small as possible, and may be 0.4 mm or less or 0.3 mm or less. It is more preferable that the fracture surface length W2 of the processed product 1 is 0.2 mm or less or 0.1 mm or less. Also, the ratio W2/t1 of the fracture surface length W2 to the plate thickness t1 of the trimmed end portion 13 of the processed product 1 may be less than 0.15, less than 0.10, less than 0.08, less than 0.06, or less than 0.04. Furthermore, the fracture surface length W2 of the processed product 1 may be 0 mm. That is, the cut end portion 13 of the processed product 1 may not have the fracture surface 13d. That is, for example, as shown in FIG. 13, the trimmed edge 13 may have a shearing surface 13c, a fractured surface 13d, and a sizing surface 13h in this order in the thickness direction of the trimmed edge 13. Alternatively, the trimmed end portion 13 may have the shearing surface 13c and the sizing surface 13h sequentially in the plate thickness direction of the trimmed edge portion 13 .

FIG. 15 is an explanatory diagram showing the volume of the corner portion 13g compressed by the pressing surface 72 of the sizing lower die 7 of FIG. 12 . As the sizing upper die 8 in FIG. 12 is pressed down toward the bottom wall 71 of the sizing lower die 7 , the corner 13g will contact the pressing surface 72 and be flattened. The material (raw material steel) of the crushed corner portion 13g moves to the shearing surface 13c side along the pressing surface 72 . When the cutting end 13 is pressed down to the position where the end surface 14a contacts the bottom wall surface 71, depending on the position and angle of the pressing surface 72, the volume V1 of the corner 13g of the second blank body 6 compressed by the pressing surface 72 will change.

As shown on the upper side of FIG. 15 , in the sizing step, the volume V1 of the corner portion 13g crushed by the pressing surface 72 should be set to be smaller than the volume V2 of the sizing space, which is the space surrounded by the extension surface 13j of the shearing surface 13c, the fracture surface 13d, and the pressing surface 72. As shown in FIG. 12, the fracture surface 13d of the cut end portion 13 of the second embryo body 6 is inclined relative to the vertical wall surface 70, and there is a gap therebetween. The volume V2 of the sizing space created by this gap becomes a space into which the material of the corner portion 13g flattened by the pressing surface 72 can flow. If the volume V2 of the sizing space is smaller than the volume V1 of the corner 13g that will be crushed by the contact surface 72, the material of the corner 13g that is crushed by the contact surface 72 cannot be completely accommodated in the volume V2, and will move toward the upper part of the sizing lower die 7.

Therefore, by making the volume V1 smaller than the volume V2, it is possible to avoid the material of the corner portion 13g crushed by the pressing surface 72 protruding beyond the extension surface 13j of the shearing surface 13c. If the volume V1 is larger than the volume V2 as shown in the lower side of FIG. 15 , the material of the corner portion 13g crushed by the pressing surface 72 protrudes beyond the extension surface 13j of the shearing surface 13c and moves toward the upper part of the sizing lower die 7 . If such a phenomenon occurs, the dimensional accuracy of the cut end portion 13 will deteriorate. Therefore, it is preferable to process so that the volume V1 becomes smaller than the volume V2 so that the corner portion 13g can be crushed by the pressing surface 72 .

As mentioned above, the manufacturing method of the processed product which concerns on 2nd Embodiment was demonstrated. According to the present embodiment, as in the first embodiment, even when a plated steel sheet having a plate thickness of more than 2.0 mm is used as a blank, a processed product 1 having excellent corrosion resistance and shape quality can be produced. Also, since there is no need to provide a gap between the trunk portion 10 of the processed product 1 and the die (or punch) pressed into the trimmed portion in the half-cutting step and the fine-cutting step, the processed product 1 having the trimmed end portion 13 flush with the trunk portion 10 can be obtained, and the end surface 14a of the opening 14 of the processed product 1 can be flattened. Moreover, the cut surface 13c can be covered with more plated layers 13f by the method of manufacturing a processed product of this embodiment, so red rust can be suppressed from occurring on the cut end portion 13 over time after the cutting process.

In addition, by performing the sizing step after the trimming step, the region of the fractured surface 13d which is the rough primary surface can be reduced, and the region where red rust occurs can be suppressed. In addition, the burrs can be flattened by sizing, and it is possible to more reliably suppress the burrs from remaining in the processed product 1 . [Example]

(Example a. The case where only the blade of the die used in the half-cutting step is set to an R shape) The shoulder (that is, the blade) of the die in the half-cutting step is set to an R shape with a predetermined radius of curvature, and a sample of a processed product is produced by the method shown in FIGS. 5 and 10 . The plated steel plate is a Zn-6%Al-3%Mg (mass ratio) alloy plated steel plate with a plate thickness t1 of 1.3~4.4mm and a plating weight of 90g/m ² (one side). The half-cutting process is carried out by using a die and a punch and using a guide to hold the plated steel plate. The inner diameter D ₃₁ of the die is 68.00mm, and the inner diameter of the punch has been changed according to the clearance C _31-41 between the die and the punch. Fine cutting is carried out by using a die and a punch to hold the plated steel plate with a guide. The shoulder (that is, the blade) of the die is set in an R shape with a predetermined radius of curvature. The punch has changed the inner diameter D ₃₂ according to the clearance C _32-42 between the die and the punch.

For each sample, the flat width Lt of the end face and the length W1 of the fractured surface after trimming were measured, and the length W2 of the fractured surface after the sizing was measured after sizing. These are calculated by using a microscope to measure at 30° intervals on the circumference of the end surface of the processed product, and calculating the average of the measured values at a total of 12 points. In addition, regarding the case where the plating layer of each sample covered the cut end, the length L of the shear plane where the plating layer was transferred from the cutting position to the cut end was measured. An electron probe microanalyzer (EPMA-WDS) was used to measure the length L of the plating layer in the trimmed end. In addition, it was judged that the presence of the plating layer was present in a part where the detection level of the Zn component was 3 times or more of the background. In addition, the object of measurement is the processed product or the 2nd green body after fine-cutting, and the processed product after fine-pressing.

In addition, in the cut end of each sample, the sheared surface, the fractured surface, and the sizing surface are as shown in FIG. 14 , and more specifically, they appear as follows.

The cut surface appears as a smooth surface at the cut end. The shear surface is caused by friction with the side of the die due to the compression (pressurization) force applied after the die touches the workpiece to cut into the workpiece. The sheared surface is produced by friction with the die, so it will show a metallic luster. In addition, fine sliding flaws in the form of streaks along the thickness direction were observed on the sheared surface.

The fractured surface is the surface where the cracks generated in the workpiece from the sheared surface side intersect and break, and it appears in the state of a matte rough surface. After the sheared surface of the processed material is formed, if the die cuts further into the processed material, the edge of the punch will generate cracks in the processed material, and at the same time, the edge of the punch will generate cracks in the processed material. The cracks generated by the punch and the die will meet each other and then penetrate. The surface where cracks are formed as described above becomes the fracture surface. The fracture surface is formed without contact between the punch and the die, so it becomes a matte rough surface. The fracture surface has an inclination corresponding to the gap (clearance) between the punch and the die.

The embossed surface appears in the state of a smooth surface after the unevenness of the fractured surface is flattened. The sizing surface is obtained by pressing a bevel-shaped or curved sizing die against the corner of the fracture surface from the lower surface side of the end of the fracture surface. The fine embossing surface is transferred through the surface roughness of the fine embossing mold, and becomes a smooth surface after the unevenness of the fracture surface is flattened.

As a method for specifying the sheared surface, the fractured surface, and the sizing surface at the cut end, there is, for example, a method of observing and measuring the shape profile of the cut end using a microscope or a contour measuring machine (contracer) based on the above characteristics.

From the viewpoint of ensuring the flatness of the end surface of the processed product when it is attached to other parts, if the flat surface length Lt of the end surface is more than 0.35 times the thickness t of the side wall of the processed product, it is evaluated as "A (good)", and if it is less than 0.35 times, it is evaluated as "B (poor)". For burrs that may cause dents or electrical shorts, those with a size of less than 0.2 mm were rated as "A (good)", and those with a size of 0.2 mm or more or those with whisker-like burrs were rated as "B (poor)". Also, regarding the end surface drop caused by the inner diameter difference D ₃₂ -D ₃₁ between the inner diameter D ₃₁ of the half-cutting die and the inner diameter D ₃₂ of the fine-cutting die, it is preferable not to produce such a drop in terms of appearance and dimensional accuracy of the product. Therefore, those with a drop of 0.5 mm or less are rated as "A (good)", and those with a drop of more than 0.5 mm are rated as "B (poor)".

In addition, the sample was subjected to an air exposure test outdoors, and the number of days until obvious red rust appeared on the cut end was observed every 15 days.

The above results are listed in Table 1. Table 1 also lists the plated steel sheets used for each sample, the conditions of the half-cutting step and the finishing step, and whether or not the corners of the cut ends are subjected to coining. Here, the plate thickness ratio (R1/t1, R2/t2) of the radius of curvature of the die is a ratio obtained by dividing the roundness given to the die shoulder by the plate thickness. Those who do not intentionally give roundness to the die shoulder (knife edge) are described as "<0.01" in this column.

[Table 1]

As shown in Table 1, the remaining length L of the plating components in Examples a1 to a19 was 0.70 times or more with respect to the plate thickness t1 of the trimmed edge. The fracture surface length W1 of the cut end of Examples a1 to a19 is all 1.0 mm or less, and shows good corrosion resistance in which red rust occurs after 60 days. In Examples a1 to a16 in which the length of the fractured surface of the trimmed end was 0.5 mm or less, good corrosion resistance was shown in which red rust was not generated after 90 days or more. In addition, in Example a15, after fine blanking, sizing processing was performed to form a sizing surface of the R surface, and the length of the side to be flattened (the width of the sizing surface) of the R surface was set to 0.6 mm. Example a16 is the person who has carried out the finishing process for forming the finishing surface of the C surface after the fine blanking, and the length of the side to be flattened (the width of the finishing surface) of the finishing surface of the C surface is set to 1.0mm and is chamfered at an angle of 45°. The fracture surface length ( W2 ) after sizing is smaller than the fracture surface length W1 of other examples. Regarding the inner diameter difference D ₃₂ -D ₃₁ between the die inner diameter D ₃₁ of the semi-cutting process and the die inner diameter D ₃₂ of the fine cutting process, it is set to 0.05 mm in the embodiments a1 to a17, to zero in the embodiment a18 (the inner diameter D ₃₁ is the same as the inner diameter D ₃₂ ) and to 1.00 mm in the embodiment a19.

In addition, according to the above characteristics, it can be confirmed from the appearance that the cut ends of Examples a1~a14, a18 and a19 have a shear surface and a fracture surface sequentially in the thickness direction, and the cut ends of Examples a15 and a16 have a shear surface, a fracture surface and a sizing surface sequentially in the thickness direction.

In contrast, the remaining length L of the plating layer components in Comparative Examples a1-a6, a8, and a10-a13 is less than 0.70 relative to the thickness t1 of the cut end of the processed product, so the number of days until red rust occurs at the cut end is less than 60 days, and the corrosion resistance is worse than that of the examples. In comparative example a9, a large negative clearance was adopted in the half-cutting step, but the press machine stopped when the load was exceeded in the half-cutting process step using a 750 kN mechanical press machine. Comparative examples a14 and a15 both showed good corrosion resistance in which red rust was formed at the cutting end after more than 90 days, but a large burr of more than 0.2mm was generated at the cutting end. In Comparative Example a7, the gap between the die and the punch in the half-cutting step was set to zero, and the plated steel sheet was completely broken in the half-cutting step.

(Example b. The case where the blades of the dies and punches used in the half-cutting step are set to an R shape) Next, the shoulders (that is, the blades) of the dies and punches in the half-cutting step are set to an R shape with a predetermined radius of curvature, and samples of processed products are produced by the method shown in FIGS. 5 and 10 . The plated steel plate is a Zn-6%Al-3%Mg (mass ratio) alloy plated steel plate with a plate thickness of 1.3~4.4mm and a plating weight of 90g/m ² (one side). The half-cutting process is carried out by using a die and a punch and holding the plated steel plate with a guide. The inner diameter of the die is 68.00mm, and the inner diameter of the punch has been changed according to the clearance between the die and the punch. Fine cutting is carried out by using a die and a punch to hold the plated steel plate with a guide. The shoulder (that is, the blade) of the die is R-shaped with a predetermined radius of curvature. The inner diameter of the punch has been changed according to the clearance between the die and the punch.

For each sample, flatness evaluation, burr evaluation, and drop evaluation were performed in the same manner as in the above-mentioned embodiment a, and the number of days for red rust to occur was investigated by an atmospheric exposure test. The result of embodiment b is listed in table 2.

[Table 2]

As shown in Table 2, the remaining length L of the plating components in Examples b1 to b19 was 0.70 times or more with respect to the thickness t1 of the trimmed end portion of the processed product. The fracture surface length W1 of the cut ends of Examples b1-b19 is all below 1.0 mm, and shows good corrosion resistance that red rust occurs after 60 days. In Examples b1 to b16 in which the length W1 of the fractured surface at the trimmed end was 0.5 mm or less, good corrosion resistance was shown in which red rust was not generated after 90 days or more. In addition, in Example b15, after fine blanking, sizing processing was performed to form the sizing surface of the R surface, and the length of the side to be flattened (the width of the sizing surface) of the R surface was set to 0.6 mm. In Example b16, after the fine blanking, the fine pressing process for forming the fine pressing surface of the C surface is carried out. The length of the side to be flattened (the width of the fine pressing surface) of the fine pressing surface of the C surface is set to 1.0mm and is chamfered at an angle of 45°. The fracture surface length (W2) after sizing became smaller than other examples. Regarding the inner diameter difference D ₃₂ -D ₃₁ between the die inner diameter D ₃₁ of the semi-cutting process and the die inner diameter D ₃₂ of the fine cutting process, it is set to 0.05 mm in the embodiments b1 to b17, to zero in the embodiment b18 (the inner diameter D ₃₁ is the same as the inner diameter D ₃₂ ) and to 1.00 mm in the embodiment b19.

In addition, according to the above characteristics, it can be confirmed from the appearance that the cut ends of Examples b1~b14, b18, and b19 have a shear surface and a fracture surface in the thickness direction in sequence, and the cut ends of Examples b15 and b16 have a shear surface, a fracture surface, and a sizing surface sequentially in the thickness direction.

In contrast, in Comparative Examples b1-b5, b7, b9-b11, and b14, the remaining length L of the plating layer components is less than 0.70 relative to the thickness t1 of the cut end of the processed product, so the number of days until red rust occurs at the cut end is less than 60 days, and the corrosion resistance is worse than that of the examples. In Comparative Example b8, a large negative clearance was adopted in the half-cutting step, but the press machine stopped due to the excess load in the half-cutting process step using a 750 kN mechanical press machine. Comparative examples b12 and b13 both showed good corrosion resistance in which red rust was formed at the cutting end after more than 90 days, but a large burr of more than 0.2 mm was generated at the cutting end. In comparative examples b6 and b15, due to insufficient negative clearance between the die and the punch in the half-cutting step, the plated steel sheet was completely broken during the half-cutting step.

From the above, in the trimming process in which the half trimming step is performed and then the finishing trimming step is performed, regarding the shape of the trimmed edge, it has been confirmed that the trimmed edge with good corrosion resistance can be obtained by setting the remaining length L of the plating component to 0.70 times or more relative to the thickness t1 of the trimmed edge of the processed product.

Above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited by these examples. And it is obvious that those who have general knowledge in the technical field of the present invention can think of various changes or amendments within the scope of the technical ideas recorded in the scope of the patent application, and know that these should also belong to the technical scope of the present invention.

For example, in the above-mentioned embodiment, although the cylindrical processed product shown in FIG. 1 was shown as an example of the processed product 1, this invention is not limited to the said example. If the processed product of the present invention is an extended shaped product, it can also be a special-shaped extended product as shown in Figure 16, and can also be a square tube extended product as shown in Figure 17. Also, Fig. 17 shows the state of the embryo body before the half-cutting step, which is to carry out the half-cutting step and the fine-cutting step along the cutting line shown by the dotted line. The processed product can also be made as shown in FIG. 16 so that only a part of the side wall of the processed product has a trimmed end flush with the outer side of the side wall.

1: Processed product 2: 1st embryo body 6: The second embryo body 7: fine pressing die 8: Fine pressing upper mold 10: Torso 11: protrusion 13:Cut ends 13c: shear plane 13d: fracture surface 13f, 13f1, 13f2: plating layer 13g: Corner 13h: Fine pressed noodles 13j: Extended surface of shear plane 13k: flat surface 14: Opening 14a: end face 15: Bottom plate 15a: Mounting surface 20: Flange 20a: remove part 31: The first die 31a: The side of the first die 32: The second die 32a: The side of the second die 41: 1st punch 41a: The side of the first punch 42: 2nd punch 42a: The side of the second punch 51: The first guide 52: The second guide 70: vertical wall 71: Bottom wall 72: Pressing surface 101: side wall 101a: Outer side 101b: Medial side of the torso 103: top wall A,B: area C _31-41,C _32-42: Clearance C _PD: Distance between the 1st die and the 1st punch at the bottom dead center D: amount of pressing L: plating component remaining length (plating layer length) Lt: Flat surface length (flat surface width) R1, R2, R11, R12: radius of curvature Rd: Surface T1: the first direction T2: the second direction t: Thickness of the side wall of the processed product t1: Plate thickness of the cut end of the processed product, plate thickness of the cut part (flange) of the first blank body t2: The remaining plate thickness of the trimmed part after the half trimming step V1: The volume of the corner part compressed by the pressing surface V2: the volume of the scouring space W1: The length of the fracture surface in the thickness direction of the cut end, the length of the fracture surface of the cut end before fine pressing W2: The length of the fracture surface between the shearing surface and the sizing surface in the thickness direction of the trimmed end, and the length of the fractured surface of the trimmed end after sizing X, Y, Z: direction

Fig. 1 is a perspective view showing an example of a processed product manufactured by a method for manufacturing a processed product according to a first embodiment of the present invention. Fig. 2 shows the cut end in area A of the processed product in Fig. 1, the left side is a sectional view on the ZX plane including the central axis of the processed product, and the right side is a side view from the X direction. FIG. 3 is a detail view of the cross-sectional view on the left side of FIG. 2 . Fig. 4 is a schematic diagram illustrating the airtightness brought about by the size of the flat surface at the end of the processed product. Fig. 5 is an explanatory diagram showing a method of manufacturing a processed product according to the embodiment. Fig. 6 is an explanatory diagram showing a half-cutting step when the blade of a die used in the half-cutting step is made into an R shape. FIG. 7 is an explanatory view showing a fine cutting step followed by the half cutting step shown in FIG. 6 . Fig. 8 is an explanatory view showing the half-cutting step when the blades of the die and the punch used in the half-cutting step are made into an R shape. FIG. 9 is an explanatory diagram showing a fine cutting step followed by the half cutting step shown in FIG. 8 . Fig. 10 is an explanatory view showing a method of manufacturing a processed product according to a second embodiment of the present invention. Fig. 11 is a schematic view showing an example of a mold used for coining. FIG. 12 is a partially enlarged view of area B in FIG. 11 . Fig. 13 shows the cut end of the processed product after the sizing step, the left side is a cross-sectional view on the ZX plane including the central axis of the processed product, and the right side is a side view from the X direction. Fig. 14 is a photograph showing an example of a trimmed end portion of a processed product after the sizing step. Fig. 15 is an explanatory view showing the volume of the corner portion crushed by the pad in the coining step. Fig. 16 is a photograph showing a special-shaped drawn product as an example of the processed product of the present invention. Fig. 17 is a photograph showing a square tube stretched product as an example of the processed product of the present invention.

13:Cut ends

13c: shear plane

13d: fracture surface

13f1, 13f2: plating layer

13k: flat surface

14a: end face

101: side wall

L: remaining length of plating components

T1: the first direction

T2: the second direction

X, Z: direction

Claims (10)

A processed product, which uses a plated steel plate with a plated layer on its surface as a blank and has a cut end portion on a hollow cylindrical side wall; the cut end portion is flush with the outer surface of the side wall of the processed product, and has a sheared surface and a fractured surface in the thickness direction of the cut end portion, or has a sheared surface, and the ratio L/t1 of the remaining length L of the plating component covered by the plated layer on the surface of the cut surface to the thickness t1 of the cut end portion of the processed product is 0 .70 or more, the length of the burr at the aforementioned cut end is less than 0.2mm. The processed product according to claim 1, wherein the length W1 of the fractured surface in the thickness direction of the trimmed end portion is greater than 0 mm and not greater than 1.0 mm. The processed product according to claim 2, wherein the length W1 of the fractured surface in the thickness direction of the cut end portion is 0.5 mm or less. The processed product according to any one of claims 1 to 3, wherein the ratio Lt/t of the flat surface length Lt of the end surface of the processed product perpendicular to the side wall to the thickness t of the side wall of the processed product is 0.35 or more. The processed product according to any one of Claims 1 to 3, wherein the cut end portion has the shear surface, the fracture surface, and the sizing surface in sequence in the thickness direction of the cut end portion, or has the shear surface and the sizing surface in sequence; and in the thickness direction of the cut end portion, the length W2 of the fracture surface between the shear surface and the sizing surface is greater than 0 mm and less than 0.5 mm. A method for manufacturing a processed product, which is a method for manufacturing a processed product that uses a plated steel plate with a plated layer on its surface as a blank and has a trimmed end on the hollow cylindrical side wall; the method includes the following steps: a half-cutting step, which is to use the first die and the first punch to cut the first blank formed from the aforementioned blank The cutting part is half-cut along the plate thickness direction, and the clearance between the first punch and the first punch is set to a negative clearance; and, the fine cutting step is to use the second die and the second punch to fine-cut the first blank body after half-cut from the same direction as the half-cut, and obtain a processed product with a cut end, and the cut end is flush with the outer surface of the side wall of the processed product; the inner diameter of the second die is D₃₂Let it be the inner diameter D of the aforementioned first die₃₁Above; let the plate thickness of the cut part of the aforementioned first blank body be t1, make the remaining plate thickness of the aforementioned cut part after the aforementioned half-cutting step be t2, in the aforementioned half-cutting step, the clearance C between the aforementioned first die and the aforementioned first punch_31-41Satisfy the following formula (a1), the radius of curvature R1 of the blade of the aforementioned first die satisfies the following formula (a2), the pressing amount D of the aforementioned first die or the aforementioned first punch to the cutting portion of the aforementioned first blank body satisfies the following formula (a3), and the distance between the aforementioned first die and the aforementioned first punch at the bottom dead center is C_PDSatisfy the following formula (a4): In the aforementioned fine cutting step, the clearance C between the aforementioned second die and the aforementioned second punch_32-42The following formula (a5) is satisfied, and the radius of curvature R2 of the blade of the second die satisfies the following formula (a6); -0.35×t1≦C_31-41≦-0.01‧‧‧(a1) 0.10×t1≦R1≦0.50×t1‧‧‧(a2) D≧0.70×t1‧‧‧(a3) C_PD≧0.20‧‧‧(a4) 0.01≦C_32-42≦0.2×t2‧‧‧(a5) 0.25≦R2≦1.50×t2‧‧‧(a6) Here, C_31-41、C_PD、C_32-42and the unit of R2 is mm. A method for manufacturing a processed product, which is a method for manufacturing a processed product that uses a plated steel plate with a plated layer on its surface as a blank and has a trimmed end on a hollow cylindrical side wall; the method includes the following steps: a half-cutting step, using a first die and a first punch to half-cut the cut part of the first blank formed from the blank along the thickness direction of the plate, and the clearance between the first die and the first punch is set to a negative clearance; and, the fine cutting step is used The 2nd die and the 2nd punch carry out fine-cutting to the aforementioned 1st green body after semi-cutting from the same direction as the aforementioned semi-cutting, and obtain the processed product having the trimmed end portion, and the trimmed end portion is flush with the outer surface of the side wall of the processed product; the inner diameter of the aforementioned 2nd die is D₃₂Let it be the inner diameter D of the aforementioned first die₃₁Above; let the plate thickness of the cut part of the aforementioned first blank body be t1, make the remaining plate thickness of the aforementioned cut part after the aforementioned half-cutting step be t2, in the aforementioned half-cutting step, the clearance C between the aforementioned first die and the aforementioned first punch_31-41Satisfy the following formula (b1), the radius of curvature R11 of the blade of the aforementioned first die satisfies the following formula (b2-1), the radius of curvature R12 of the blade of the aforementioned first punch satisfies the following formula (b2-2), the pushing amount D of the aforementioned first die or the aforementioned first punch to the cutting portion of the aforementioned first blank body satisfies the following formula (b3), and the distance between the aforementioned first die and the aforementioned first punch at the bottom dead center is C_PDSatisfy the following formula (b4); in the aforementioned fine cutting step, the clearance C between the aforementioned second die and the aforementioned second punch_32-42The following formula (b5) is satisfied, and the radius of curvature R2 of the blade of the second die satisfies the following formula (b6); -0.45×t1≦C_31-41≦-0.10×t1‧‧‧(b1) 0.10×t1≦R11≦0.65×t1‧‧‧(b2-1) 0.10×t1≦R12≦0.65×t1‧‧‧(b2-2) D≧0.70×t1‧‧‧(b3) C_PD≧0.20‧‧‧(b4) 0.01≦C_32-42≦0.2×t2‧‧‧(b5) 0.25≦R2≦1.50×t2‧‧‧(b6) here, C_31-41、C_PD、C_32-42and the unit of R2 is mm. The method for manufacturing a processed product according to claim 6 or 7, which further includes a finishing step, wherein the processed product obtained in the fine cutting step is used as a second blank, and the corners of the cut ends of the second blank are pressed against a pad to obtain a processed product with a fine-pressed surface formed at the corner. The method of manufacturing a processed product according to claim 6 or 7, wherein the difference D ₃₂ -D ₃₁ between the inner diameter D ₃₁ of the first die and the inner diameter D ₃₂ of the second die is 1.00 mm or less. The method for manufacturing a processed product according to claim 6 or 7, wherein a preparatory step is further included before the half-cutting step, and the preparatory step is to form a first green body having a hollow side wall and a flange from a flat plate-shaped plated steel sheet.

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