Double-deck hemming die

Abstract

To provide a die capable of suppressing thrust load without damaging the die or adversely affecting a machine device by performing a crushing process in a single operation instead of multiple times of operations in order to reduce the thrust load that occurs when performing the crushing process on an acutely bent plate material, and also provide a die that prevents the workpiece from being pushed forward (worker side) by the thrust load during the crushing process and reducing the work efficiency of the crushing process.SOLUTION: A projection 7 provided on the lower part of an upper die 1 enters a groove 4 of a lower die 2 to suppress the thrust load generated during a crushing process, thereby simplifying the process to a single crushing process. Furthermore, a V-groove 5 for acute bending is formed at an asymmetric angle with respect to a die core 8, enabling more acute bending, preventing damage to the die due to thrust load, and preventing a workpiece from being pushed toward a worker side, thus improving work efficiency.SELECTED DRAWING: Figure 1, Figure 8

Description

Detailed Description of the Invention

Technical Field

[0001] The present invention relates to a hemming die that can simplify the conventional multi-step working process, which was previously carried out in multiple steps to prevent the die and mechanical devices from being damaged by the thrust load, into a single hemming process during the hemming process of hemming.

Background Art

[0002] There is a double-deck type die that performs the acute-angle bending and hemming processes without changing the die. This is a die in which the lower die 24 is placed on the die support die 16, and the upper die 23 is attached to the lower die 24 via a collar 10 and a stripper bolt 9 so as to be vertically movable. The upper die 23 has a built-in coil spring 11 in the lower die 24, and the stripper bolt 9 that joins the lower die 24 and the upper die 23 is urged upward. Further, an acute V-groove 17 for bending the plate material W1 at an acute angle is formed on the upper surface of the upper die 23. Then, the plate material W1 is bent at an acute angle by the V-groove 17 and the punch 15. The plate material W2 bent at an acute angle is placed between the upper die hemming surface 6 and the lower die hemming surface 3, and the punch is pressed from above in a state where it is engaged with the V-groove 17 of the upper die 23, and the pressing is performed in 2 to 3 steps to reduce the thrust loads S1, S2, and S3 in FIG. 3, and the hemming process is performed. (Patent Document 1)

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0003] The thrust load is the force generated when squeezing a sheet metal bent at an acute angle, and refers to the loads S1, S2, and S3 that are pushed forward (towards the operator side) as shown in Figure 3. In the conventional mold shown in Figure 2, when squeezing the sheet metal bent at an acute angle in one go, the thrust load acts strongly forward. Therefore, as shown in Figure 2, a force acts on the stripper bolt 9 that combines the lower die 24 and the upper die 23, and due to repeated expansion and contraction, metal fatigue accumulates and finally breaks. Furthermore, it also has an adverse effect on the accuracy of the machine body. Therefore, it is ideal to perform the squeezing process in two to three steps to reduce the thrust load.

[0004] However, many workers who want to simplify the squeezing process performed in two to three steps often perform the squeezing process in one go while being aware of the risks, and the stripper bolt 9 often breaks, and the machine body and the mold are often damaged. Therefore, a mold that can safely perform the squeezing process in one go is desired.

[0005] In the squeezing process, the thrust load acts proportionally forward according to the thickness and material of the workpiece and the angle of the workpiece W2 bent at an acute angle. Especially when the angle of the workpiece bent at an acute angle is large, the thrust load increases, and the workpiece is pushed forward at the beginning of the squeezing, resulting in a decrease in the workability of the squeezing process.

[0006] To solve the problem of the large acute bending angle, the acute bending angle of the workpiece W2 can be reduced. However, as shown in Figure 7, the conventional angle-symmetric 30° punch 15 is made in a size such that the front side of the workpiece does not hit the machine body. If it is made into an acute punch that does not hit the machine body, it will become a large and costly punch. Means for solving the problem

[0007] The mold of the present invention is made in view of the current problems as described above, and is a mold as shown in FIG. 1. A protrusion 7 for suppressing the thrust load, which is provided at the lower part of the upper die 1 in the groove 4 for suppressing the thrust load of the lower die 2, slides up and down to suppress the thrust load generated during the coining process. Further, when the upper die 1 is provided on the lower die 2, it is joined by a stripper bolt 9 via a collar 10. This collar 10 and bolt 9 also serve to suppress the thrust load. That is, the thrust loads S1 and S2 acting forward at the upper and lower two positions of the bolt 9 and the groove 4 are suppressed. Furthermore, by changing the angle-symmetric 30° V-groove 17 of the conventional mold to an angle-asymmetric V-groove 5, acute-angle bending becomes possible, and the work piece W2 is not pushed forward by the thrust load S3 during the coining process, improving workability, eliminating breakage of the bolt 9 and damage to the mold and the machine body, and enabling the coining process to be performed in a single working step.

[0008] The angle-asymmetric V-groove 5 of the mold of the present invention is as shown in the example of FIG. 8, with the rear angle smaller than the front angle. The front angle of 15° is the same as that of the conventional mold shown in FIG. 7, and is an angle at which the acute-angle-bent front work piece W2 does not hit the machine body. The rear angle is set to 10° for bending at a sharper angle than before. When bending with an angle-asymmetric punch 22 adapted to this V-groove, the acute-angle bending angle of the work piece W2 becomes 25° as shown in FIG. 9, reducing the thrust load during the coining process and improving workability. Note that this rear angle is set to be 0° to less than 15°.

[0009] FIG. 11 is a diagram showing an example in which only the cutting edge of the angle-symmetric 30° punch 15, which has been widely used conventionally, is modified according to the angle of the angle-asymmetric V-groove 5 of the mold of the present invention shown in FIG. 8. The punch angle is set to 25° with a front angle of 15° and a rear angle of 10°, making it usable for the mold of the present invention.

[0010] When performing sheet metal bending with an angle-asymmetric mold, a thrust load is applied to the side with the larger angle, so it is necessary to provide a thrust receiver on the opposite side. In the angle-asymmetric V-groove 5 of the mold of the present invention, since the angle on the front side is larger, a thrust load is applied to the front side. However, the stripper bolt via the collar, and the two locations of the lower protrusion and groove function as thrust receivers, and the thrust load during acute-angle bending can be suppressed. Effects of the Invention

[0011] How the thrust load acts will be described below with reference to FIGS. 4, 5, and 6. This is a verification of crushing the work SPCC 1.6t in one go without dividing it into multiple times. First, the verification in FIG. 4 is a verification of acute-angle bending at 30° using the conventional mold, punch 30°, and acute-angle V-groove 30° shown in FIGS. 2 and 3. As shown by the dial gauge scale 21, it can be confirmed that the lower part of the upper die 1 protrudes greatly forward due to the thrust load as the crushing angle 20 becomes smaller. Due to this thrust load, the stripper bolt 9 is pulled and broken, damaging the mold and disturbing the accuracy of the machine body. The numerical value in parentheses of the dial gauge scale 21 below the upper die in the figure represents the dimension in mm by which the upper die protrudes forward due to the thrust load, and the numerical value in parentheses of the crushing angle 20 represents the degree. Since the display of the dial gauge scale and the display of the crushing angle described in FIGS. 5 and 6 below are the same, this explanation will be omitted.

[0012] FIG. 5 is a verification of using the mold of the present invention and the conventionally widely used symmetric 30° punch 15 without modification and performing crushing in one go.

[0013] FIG. 6 is a verification of using the angle-asymmetric punch 22 of FIG. 11, which is obtained by cutting and modifying the mold of the present invention and the conventionally widely used symmetric 30° punch 15 to 10° only on the rear side of the punch core, and performing crushing in one go.

[0014] First, comparing the results of FIG. 5 of the mold of the present invention with those of the conventional mold and FIG. 4, it can be seen that the scale (mm) of the dial gauge attached below the upper die is smaller in the mold of the present invention. This indicates that the thrust loads acting forward at the upper and lower positions of the bolt 9 and the groove 4 of the mold of the present invention are reduced.

[0015] Next, comparing the results of FIG. 5 and FIG. 6 of the mold of the present invention, it can be seen from the scale of the dial gauge that the thrust load is reduced in FIG. 6. This is due to the effect of setting the acute-angle bending to 25°, which is smaller than 30°, and it can be seen that the load is reduced.

[0016] The mold of the present invention is not only used in combination with the angle-asymmetric punch 22 described above. As shown in the verification of FIG. 5 and FIG. 10, it can be used as it is without modifying the conventionally widely used angle-symmetric 30° punch 15.

[0017] As shown in the verification of FIG. 5, when the acute-angle bending is a general 30°, the mold of the present invention can perform the crushing process in one step because the thrust load is significantly reduced compared to the conventional mold. However, in the case of thick plates or special hemming with a short flange for corner hemming, the workpiece may be pushed forward at the beginning of the crushing. For such hemming, by combining the angle-asymmetric punch shown in FIG. 6 and bending at a sharper angle, safe and efficient work becomes possible.

[0018] The verification in FIG. 6 was carried out by modifying the conventional angle-symmetric 30° punch 15 shown in FIG. 11 to an angle-asymmetric punch 22 in order to maximize the effect of the mold of the present invention. Although the scale of the dial gauge indicating the thrust amount is small, it represents the value where the upper die protrudes forward. This value is the clearance value provided for the upper die 1 to slide up and down on the lower die 2. Except for this value, the amount by which the V-die protrudes forward due to the thrust load is equal to zero.

[0019] Comparing FIG. 5 and FIG. 6 which show the verification results using the mold of the present invention with FIG. 4 which shows the verification results of the conventional mold, it can be remarkably seen that the thrust load of the mold of the present invention is significantly reduced.

[0020] As shown in FIG. 2, in the hemming mold of the prior art, since the length of the slide portion where the upper die 23 slides up and down on the lower die 24 is short, stable bending accuracy could not be maintained due to wear of the slide portion. However, as shown in FIG. 1, in the mold of the present invention, since a protrusion 7 for suppressing the thrust load is provided at the lower part of the upper die 1, the slide portion with the lower die 2 becomes longer, so that wear during vertical sliding can be suppressed, and stable bending accuracy can be maintained.

[0021] By modifying the cutting edge of the angle-symmetric 30° punch 15 that has been widely used conventionally, an expensive acute-angle high-height punch is no longer required, which is economical.

Best Mode for Carrying Out the Invention

[0022] Explaining while referring to FIG. 1, the upper die 1 provided with a protrusion 7 and an angle-asymmetric V-groove 5 for suppressing the thrust load is vertically slidably joined to the upper die threaded hole 14 by a stripper bolt 9 via a collar 10 to a lower die 2 having a lower die crushing surface 3 on which the acutely bent plate material W2 can be placed and provided with a groove 4 for suppressing the thrust load.

[0023] The lower die 2 is provided with a long hole for the stripper bolt 9 to slide up and down, and the upper die 1 is pushed upward from below by a coil spring 11 via the stripper bolt and fixed by a screw thread 12.

[0024] The angle-asymmetric V-groove 5 provided at the upper part of the upper die 1 can use the angle-symmetric 30° punch 15 that has been more widely used conventionally, and also, an angle-asymmetric punch 22, FIG. 11, which is modified to bend this punch at a more acute angle, can also be used.

[0025] As described above, according to the present invention, in order to reduce the thrust load generated in the hemming process, the hemming operation that was previously performed in two or three steps can now be carried out in one step, resulting in a double-deck mold that significantly reduces the working time. Moreover, a safe mold that greatly reduces the dangerous thrust load can be provided.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Explanation of Reference Numerals

[0027] 1. Upper die 2. Lower die 3. Lower die crushing surface 4. Groove for suppressing thrust load 5. Angle-asymmetric V-groove 6. Upper die crushing surface 7. Protrusion for suppressing thrust load 8. Metal core 9. Stripper bolt 10. Collar 11. Coil spring 12. Screw thread 13. Elongated hole 14. Upper die thread hole 15. Angle-symmetric 30° punch 16. Die support die 17. Angle-symmetric 30° V-groove 18. Machine body (intermediate plate) 19. Cutting part (hatched part) of angle-symmetric 30° punch modification 20. Crushing angle (degrees) 21. Dial gauge scale (mm) 22. Angle-asymmetric punch 23. Upper die of prior art 24. Lower die of prior art W1. Plate material W2. Plate material bent at acute angle S1. Thrust load where the punch protrudes forward S2. Thrust load where the lower die protrudes forward S3. Thrust load where the workpiece jumps out forward

Claims

Claim 1 A double-deck mold for hemming a sheet material, comprising a lower die having a flattening surface for flattening the sheet material, and an upper die located above the lower die and having a surface for flattening the sheet material from above. On the upper surface of the upper die, a V-groove for bending the sheet material at an acute angle is formed at an asymmetric angle with respect to the mold core, and a protrusion for suppressing the thrust load is formed at the lower part. The lower die is provided with a groove for suppressing the thrust load applied during the flattening process when the upper die slides up and down. A double-deck hemming mold characterized by the above.

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