JPS6365409B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method of forming a flanged perforated cylinder. [Prior art and its problems] The following methods are conventionally known as methods for obtaining an integrally molded product of a thin plate with a flange and a perforated cylinder. Burring method from perforated material. Stretch flange forming method using circular pipes as material. Overhanging and drilling (punching, cutting)
A combination molding method of and burring processing. A forming method that combines deep drawing, drilling, and burring. A combination forming method of deep drawing and edge cutting. Spinning method for perforated blank plates and circular tubes. However, these methods have problems in terms of restrictions on molding height and flange area, number of steps, workability, and productivity. For this reason, the inventors have decided to
In No. 1082435, we proposed a method for forming cylinders using opposing hydraulic pressure. In this method, deep drawing is performed by pushing a perforated blank into a hydraulic chamber with a punch, and then burring is performed by reducing the opposing hydraulic pressure and pushing the punch further.Compared to the above methods, The molding height can be increased and the molding can be performed efficiently in one process. Therefore, in this method, the raw plate is pressed against the punch shoulder and the punch bottom by opposing hydraulic pressure, and the stretch flange deformation is suppressed by the frictional force generated in those areas. Therefore, by making the punch shoulder radius rp as small as possible and increasing the punch pushing area per unit stroke at the beginning of the stroke, the hydraulic pressure gradient created is steeper. The expansion of the hole was suppressed by increasing the resistance required for bending and unbending deformation. However, when the punch shoulder radius is made small in this way, there is a problem in that a shape defect (straightness of the side wall portion) occurs during the next step of burring, and the shape accuracy of the molded product decreases. In other words, when the punch shoulder radius is made small, a sharp bending deformation occurs during the deep drawing process in the first stage, and bending deformation occurs at the punch shoulder during the burring process in the second stage because the radial tension at the bottom of the punch is small. There is insufficient tensile force to bend the part back. Therefore, it is unavoidable that a bulge due to bending deformation at the punch shoulder remains in the side wall formed by stretch flange deformation, or that a wide ring-shaped constriction appears on the outer surface of the side wall. [Means for Solving the Problems] The present invention was developed through research in order to solve the above-mentioned problems, and its purpose is to achieve good shape accuracy and to reduce the molding height. The object of the present invention is to provide a method for forming a perforated cylinder with a flange, which can be made to have an extremely high quality equivalent to that of a plain plate without holes. To achieve this object, the present invention uses a punch with a large shoulder radius and is capable of preventing stretch flange deformation during the deep drawing process. In the method of forming a cylinder into a cylinder using the direct facing hydraulic pressure forming method, a counter plate facing the punch is positioned in the hydraulic chamber, the counter plate presses the base plate against the bottom of the punch, and by further pushing the punch, both sides of the base plate are formed. A process of deep drawing while applying compressive force to increase stretch flange deformation resistance;
Molding is performed by lowering the counter plate, removing opposing hydraulic pressure, and pushing in the punch. In the present invention, the punch shoulder radius of the punch is preferably about 10 times or more the thickness of the blank plate, thereby improving both the limit drawing ratio and the shape accuracy in a well-balanced manner. [Examples] Examples of the present invention will be described below with reference to the accompanying drawings. Figures 1 a to d and Figure 2 show the principle of the method of forming a flanged perforated cylinder according to the present invention. A pressure medium liquid 3 such as water or the like is filled. 4 is a punch facing the hydraulic pressure chamber 2, 5 is a wrinkle presser plate facing the upper surface of the die, 9 is a blank plate, 1
0 is a hole formed concentrically with the blank plate. In the present invention, it is desirable to use the punch 4 with a large shoulder radius rp, generally about 7 times or more, preferably 10 to 20 times, the thickness of the plate. Reference numeral 6 denotes a counter plate arranged in the hydraulic pressure chamber 2 so as to face the punch 4. A sealing material 7 such as an O-ring is attached to the upper surface of the counter plate 6, which corresponds to the outside of the hole 10 in the blank plate. Although the top surface shape is horizontal in the illustrated example, it may be a spherical concave surface depending on the punch diameter and punch shoulder radius. Further, a support member 8 having a smaller cross-sectional area than this is provided at the back of the counter plate 6, and this support member 8 penetrates the bottom of the hydraulic pressure chamber 2 and is connected to a force applying means 11 such as a fluid pressure cylinder or a spring. It is. For forming, first, as shown in FIG. 1a, a blank plate 9 with a hole 10 formed concentrically with the punch in the center is placed on the upper surface of the die. At this time, applying means 1
1, the counter plate 6 is raised via the support member 8 to a position on or near the die surface of the hydraulic pressure chamber 2. Next, the press is operated, and the wrinkle presser plate 5 is lowered to press the blank 9 between it and the upper surface of the die, and then the punch 4 is lowered so that the punch bottom 40 becomes blank as shown in the imaginary line in FIG. 1a. At the same time as or just before the plates 9 come into contact, a pressing force f is applied to the counter plate 6 by the force applying means 11, and the blank plate 9 is sandwiched between the punch bottom portion 40 and the counter plate 6. The pressing force f may be such that the sealing material 7 comes into close contact with the outer periphery of the hole 10 in the blank plate, and therefore a force of several hundred kg at most to about one ton at most is sufficient. In this state, the punch 4 is further pushed into the hydraulic pressure chamber 2. FIG. 1b and FIG. 2 show the state at this time, in which an opposing hydraulic pressure q is generated in the hydraulic pressure chamber 2 due to the pushing of the punch 4, and this opposing hydraulic pressure causes the blank plate 9 to press against the punch shoulder 41 and It is wrapped around the side wall of the punch, creating a friction-retaining effect. At the same time, since the lower surface of the counter plate 6 is strongly pressed by the opposing hydraulic pressure q, a compressive force F is applied to the lower surface of the blank plate 9 through the counter plate 6, and this automatically increases as the generated hydraulic pressure increases. Therefore, the operation of the force applying means 11 may be stopped from the moment the opposing hydraulic pressure is generated. Then, the blank plate 9 is pulled into the hydraulic chamber 2 by the downward movement of the punch 4 while its upper and lower surfaces are pinched by the punch bottom 40 and the counter plate 6, and the first
As shown in Figures b and c, deep drawing is performed from the beginning of the process. The present invention does not simply suppress the expansion of the hole 10 by holding friction between the punch shoulder and the side wall using opposing hydraulic pressure as the punch is pushed in, but also applies a compressive force from the beginning of the stroke by applying a counter plate 6 to the holed bottom of the blank plate. Since the punch bottom part 40 is formed while applying a frictional restraining force to both sides of the blank plate, the stretch flange deformation resistance is increased even though the punch shoulder radius is made larger than 10 times the thickness of the blank plate. As a result, the deep drawing limit is significantly improved. When a predetermined molding height is obtained, at that point, as shown in FIG. 1d, the counter plate 6 is retreated to the lower part of the hydraulic pressure chamber, and at the same time, the hydraulic pressure is released, and in this state, the punch 4 is further pushed in. Perform stretch flange forming. The punch shoulder radius rp is large, more than 10 times the plate thickness, and the bending deformation caused by the punch shoulder 41 in the pre-stage deep drawing process is gentle, so there is no shortage of tensile force to unbend the deformed part, and the work is smooth. Stretch flange forming is performed. Therefore, no bulge occurs in the molded side wall portion, resulting in extremely good straightness. Forming is completed with the above steps, punch 4 and wrinkle press plate 5
When the force applying means 11 is activated after raising the counter plate 6, the molded product (perforated cylinder with flanges) 12 is knocked out. By stopping the counter plate 6 in the same position, it is prepared for the next cycle. FIG. 3 shows an example of an apparatus used for carrying out the present invention, in which a dome 13 is provided at the bottom of the die 1, a bottom cover 14 having a seal ring 15 is attached to the bottom of the dome 13, and a dome 14 is attached to the bottom of the dome 13. is provided with a hydraulic pressure conduit 16, which connects an auxiliary pump 17 and a relief valve 1.
8. As for the method of applying the opposing hydraulic pressure, it is preferable to use a forced pressurization method in which pressure is increased from the beginning using an auxiliary pump 16 as shown in FIG. 3, but of course a natural pressure increase method using only punching may also be adopted. Next, concrete implementation results of the present invention will be explained. Example 1 Thickness of a blank plate with concentric holes drilled in the center
0.6mm SPCE material was used. Its mechanical properties are shown in Table 1 below.

〔Effect of the invention〕

According to the present invention as described above, a flanged perforated cylinder with an extremely large forming height, which is the same as the deep drawing limit of a blank blank plate, and excellent shape accuracy with good side wall straightness, can be produced in one stroke. It can be easily molded, and the molded product can also be easily taken out, providing excellent effects.

[Brief explanation of drawings]

Fig. 1 is an explanatory view showing the forming process of the flanged perforated cylinder forming method according to the present invention, Fig. 2 is an enlarged view of the initial stage of forming in Fig. 1, and Fig. 3 is an illustration of the apparatus used to carry out the present invention. Cross-sectional view showing an example, No. 4
The figures are hydraulic pressure-punch stroke diagrams of the present invention and the conventional method, Figures 5 a and b are perspective views of the molded product obtained by the present invention, Figure 6 is a perspective view of the molded product obtained by the conventional method, and Figure 7 Figures a and b are enlarged diagrams showing the measurement results of the side wall straightness of the molded product of the present invention, and Figures 8a and b are enlarged diagrams showing the measurement results of the side wall straightness of the molded product of the conventional method. 1...Dice, 2...Hydraulic pressure chamber, 4...Punch, 5...Wrinkle holding plate, 6...Counter plate, 8...Support member, rp...Punch shoulder radius.

Claims (1)

[Claims] 1 In a method of forming a blank plate with a hole in the center into a cylinder by direct facing hydraulic pressure forming method, a counter plate is positioned in the hydraulic pressure chamber, the blank plate is pressed against the bottom of the punch by the counter plate, and the punch is further pressed. With flanges, the process consists of a deep drawing process in which compressive force is applied to both sides of the blank plate by pushing in, increasing stretch flange deformation resistance, and a burring process in which the counter plate is lowered and the opposing hydraulic pressure is removed and the punch is pushed in. Forming method for perforated cylinders.