JPH10166067A - Method for hemming and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hemming method and a hemming device where all of flange-bending on the circumferential edge of a hole, pre-hemming (pre-bending) and hemming (regular bending) are executed within one process following to piercing at the time of hemming on the circumferential edge of the hole. SOLUTION: An insert punch 9, a pad 5 and a work W are restricted, a sectional die 4 is pressed in the insert punch 9 and a hemming flange part F is formed. Further, the sectional die 4 is pressed and a recessed seat part Q is formed, and the hemming flange part F formed in advance is made into a pre-hemming state. In the process of raising of the sectional die 4, the recessed seat part Q is returned to the original state, the hemming flange part F is bent back completely and hemming is completed in one process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hemming method and a hemming apparatus which are one of typical forms of press bending, and particularly to a method for hemming a peripheral portion of a hole formed in a work in advance. , Flange bending,
The present invention relates to a hemming method and a hemming apparatus capable of performing three steps of preheming (preliminary bending) and hemming (main bending) in substantially one step.

[0002]

2. Description of the Related Art A curling method similar to hemming is disclosed in Japanese Patent Application Laid-Open No. 148532/1995.

[0003] In this conventional curling method, FIG.
As shown in (3), there are three steps of piercing (piercing) processing, bar link processing, and restriking & curling processing. In the piercing processing, a plate-shaped work W is restrained by pressing with a die 51 and a pad 52. Then, the punch 53 is lowered, and the piercing hole P is punched and formed by the shearing action between the die 51 and the punch 53. On the other hand, in the bar link processing step, the work W on which the piercing hole P has been previously formed is pressed and constrained by the die 61 and the pad 62, and then the punch 63 is pressed into the die 61 to thereby form the piercing hole P.
Is bent at a right angle to form a flange portion F.

Further, in the restoring and curling process, the workpiece W is positioned on the die 71 such that the previously formed flange portion F is fitted to the convex portion 71a of the die 71, and then the punch 73 is lowered. Let it. Thereby, the flange portion F is bent outward along the curved surface 71b of the die 71, and the curl portion 74 is formed on the entire peripheral portion of the pierce hole P.

[0005] Such a processing form is often used, for example, in a wiring (wire harness) hole formed in an automobile body panel, and the wiring is inserted as it is without using a rubber grommet. In addition, the wiring itself can be protected from damage and the like.

[0006]

The conventional curling method requires at least two steps of burring and restriking and curling in addition to the piercing hole processing, which leads to an increase in the number of steps. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in performing hemming on the peripheral portion of a hole, a flange bending process on the peripheral portion of the hole is performed in one step following the piercing hole processing. It is an object of the present invention to provide a hemming method and a hemming apparatus capable of performing all of pre-hemming (preliminary bending) and hemming (main bending).

[0008]

According to the first aspect of the present invention, there is provided an annular insert punch elastically supported by a punch so as to be vertically movable, and a die opposed to the insert punch.
And a pad elastically supported so as to be able to move up and down on the die. A flange bending step of forming a hemming flange by bending the outer periphery of the hole toward the insert punch by pressing the die into the insert punch in a state where the outer portion is pressurized and restrained by the punch including the insert punch and the pad. By pressing the die still into the insert punch side following the flange bending process, the insert punch is temporarily separated from the work, and the portion of the work that has been constrained by the insert punch is then replaced by the insert punch. A pre-heming step of forming a seat by bending in the movement direction; In the process of returning the insert punch to the initial state together with the die after the end, including a hemming step of correcting the seat to its original state while bending the hemming flange so as to overlap the seat. I have.

According to a second aspect of the present invention, in the pre-hemming step of the first aspect of the present invention, the outer portion of the hemming flange is pulled in the moving direction of the die by frictional force between the die and the hemming flange. It is characterized by forming a part.

According to a third aspect of the present invention, in the pre-hemming step of the second aspect of the present invention, the stepped portion on the outer periphery of the die is engaged with the base portion of the hemming flange portion to prevent the die from moving. Accordingly, the seat portion is formed by drawing the outer portion of the hemming flange in the moving direction of the die.

According to a fourth aspect of the present invention, there is provided a hemming apparatus for use in the hemming method according to the first aspect, wherein the insert punch is supported on the punch via an elastic body so as to be vertically movable. While the lower die is formed by the punch and the insert punch, the upper holder is fixed with a sectional die that can be inscribed in the insert punch, and the pad is elastically supported by the upper holder so as to be vertically movable. The upper die is formed by the upper holder, the sectional die and the pad.

According to a fifth aspect of the present invention, there is provided the sectional die according to the fourth aspect of the present invention, wherein a stepped portion is formed on an outer peripheral surface of the sectional die to be engaged with a root of the hemming flange after the flange bending. It is characterized by having.

Therefore, according to the first aspect of the present invention,
In the process of inserting the insert punch into the die,
In the first half, the hemming flange is bent by the cooperation of the insert punch and the die, and in the second half, the outer part of the hemming flange of the work is moved in the same direction as the insert punch while the insert punch is once separated from the work. The seat is formed by being retracted.

Thus, the hemming flange has a predetermined inclination with respect to the insert punch so that the pre-hemming process can be performed by the insert punch.
When the die and the insert punch start to move in the opposite direction to return to the initial state, the seat is corrected to return to the original state, and the hemming flange is folded back so as to overlap with the seat. Hemming is completed.

According to the second aspect of the present invention, in the pre-heming state in which the outer portion of the hemming flange is formed as a seat, the frictional force between the die and the hemming flange causes the hemming flange to be in the pre-hemming state. The outer portion is pulled into the insert punch side, and in the invention according to claim 3, the stepped portion on the outer periphery of the die is engaged with the root portion of the hemming flange portion, in addition to the frictional force described above, The outer portion of the hemming flange portion is forcibly drawn into the insert punch side by the moving force of the die.

According to the fourth aspect of the present invention, in the process of lowering the upper die including the upper holder, the sectional die, and the pad, the lower die including the punch and the insert punch is lowered. Is achieved.

According to the fifth aspect of the present invention, the stepped portion on the outer periphery of the sectional die on the upper die side engages with the base of the hemming flange, so that the outer portion of the hemming flange is inserted. It is drawn down with a punch.

[0018]

According to the first and second aspects of the present invention, while the die is being pressed into the annular insert punch, flange bending and subsequent pre-hemming are performed, while the die comes out of the insert punch. When the hemming flange starts to reversely move in the direction, the hemming flange portion is folded back so as to overlap with the workpiece and hemmed, so that all the processing necessary for hemming can be performed in one step other than the piercing hole processing. As a result, the number of processing steps and the number of manufacturing steps for the press die are greatly reduced, and the cost of the molded product can be reduced.

According to the third aspect of the present invention, during pre-hemming, the die is moved by the engagement between the stepped portion on the outer periphery of the die and the hemming flange in addition to the frictional force between the hemming flange and the die. Since the force is applied, the seat portion can be formed by bending the outer portion of the hemming flange portion more reliably, and in addition to the same effects as the inventions according to claims 1 and 2, the reliability of the pre-hemming process is improved. There are benefits to improve.

According to the fourth aspect of the present invention, each step in the first aspect of the invention progresses in the process of lowering the upper mold with respect to the lower mold. Similarly, the cost of the molded product can be reduced by reducing the number of processing steps and the number of manufacturing steps of the press die.

According to the fifth aspect of the invention, since the stepped portion is formed on the outer periphery of the sectional die which is a part of the upper die, the pre-hemming is performed in exactly the same manner as the third aspect of the invention. There is an advantage that processing reliability is improved.

[0022]

1 to 6 show a preferred embodiment of the present invention. A harness formed on a vertical wall portion of a hood ridge lower panel (hereinafter referred to as a work) W of an automobile shown in FIG. An example of a case where hemming is performed on a peripheral portion of the insertion hole H is shown. That is, (A) to (D) of FIG.
Shows the flow of a series of steps until the hemming process is completed, and FIGS. 2 to 5 show details of each step shown in FIGS. 1A to 1D. Incidentally, the hood ridge lower panel W is finally connected to the hood ridge 8 as shown in FIG.
1 and side member 82 and strut housing 83
Welded with etc. Reference numeral 84 denotes a wire harness inserted into the harness insertion hole H.

As shown in FIG. 2, the press die is roughly divided into an upper die 1 and a lower die 2. A sectional die 4 having a solid stepped cylindrical shape is fixed to an upper holder 3 serving as a main body of the upper die 1, and a pad 5 is arranged so as to surround the sectional die 4.
As is well known, the pad 5 is supported on the upper holder 3 via a pad retainer for regulating a vertical stroke with respect to the upper holder 3 and an elastic body such as urethane rubber (both not shown) so as to be vertically movable.

On the other hand, the lower die 2 has a cylindrical concave portion 7 formed in a part of the punch 6 also serving as a lower holder, and the concave portion 7 has an annular bottomed ring via an elastic body 8 such as urethane rubber. The insert punch 9 is arranged so as to be movable up and down, and a die receiving recess 10 that can receive the sectional die 4 is formed on the upper surface of the insert punch 9. And lower mold 2
When the upper die 1 is lifted up and separated from the elastic body 8 and the elastic body 8 is in a free extension state, the upper surface of the insert punch 9 and the upper surface of the punch 6 are set to be flush.

A part of the outer periphery of the sectional die 4 is partially cut out so as to be able to enter the die receiving recess 10 of the insert punch 9 to form a stepped portion 11. A plurality of oil breakers 12 are arranged at a constant pitch in a portion facing the upper surface of the peripheral portion of the punch 9. The oil breaker 12 includes a plunger 13 urged by a compression coil spring (not shown).
The work W is attached to the pressing surface 5a of the pad 5 due to oil and the like while suppressing the spring back of the concave seat portion Q immediately after molding as described later. It has a function to prevent sticking.

Therefore, according to the present embodiment, FIG.
2 (A) and FIG. 2, in the state where the upper die 1 is at the top dead center position, the work W which has been subjected to the piercing hole processing in the previous process, that is, the work W in which the harness insertion hole H has been formed in advance.
Is put on the lower mold 2 and the center of the harness insertion hole H and the center of the insert punch 9 are positioned. At this time, it goes without saying that the diameter of the die receiving recess 10 on the insert punch 9 side is larger than the diameter of the harness insertion hole H.

When the upper die 1 is lowered when the work W is positioned on the lower die 2, the pad 5 is pressed against the work W, and the pad 5, the punch 6 and the insert punch 9 form the work W. The periphery of the harness insertion hole H is restrained by pressing. At this time, since the spring constant of the oil breaker 12 is much smaller than that of the elastic body 8, the oil breaker 1
The second plunger 13 is retracted until it is flush with the pressing surface 5a of the pad 5.

If the upper die 1 still descends from this state,
As shown in FIG. 1 (B) and FIG. 3, the sectional die 4 enters the die receiving recess 10 of the insert punch 9, and forms a hemming flange portion F by bending the periphery of the harness insertion hole H downward as a flange bending process. .

In this case, since the flange height of the hemming flange portion F to be formed is 10 mm or less and does not require a large forming force, the elastic body 8 does not compressively deform and has a sufficient strength for the flange forming force. It becomes a form to oppose.

When the upper die 1 further descends after the flange bending as described above, the lower surface 4a of the convex portion of the sectional die 4 comes into contact with the inner bottom surface of the die receiving concave portion 10 of the insert punch 9, so-called bottom contact. As shown in FIGS. 1C and 4, the insert punch 9 is forcibly pushed down with the compression deformation of the elastic body 8, and eventually the stepped portion 1 of the sectional die 4.
1 comes into engagement with the root of the hemming flange F formed earlier.

As a result, the insert punch 9 is pushed down to below the tip of the hemming flange portion F while temporarily separating from the work W, and the hemming flange portion F has a stepped portion in addition to the frictional force with the sectional die 4. Since the pressing force of the sectional die 4 due to the engagement with the section 11 is applied, as shown in FIG. 4, the portion of the work W outside the hemming flange portion F, that is, until the upper die 1 reaches the bottom dead center. The portion restrained by the insert punch 9 is bent downward as a pre-hemming process to form a concave seat Q. That is, the hemming flange portion F has a predetermined inclination due to the formation of the concave seat portion Q so that the hemming process by the insert punch 9 can be performed.

Here, assuming that the flange height of the hemming flange portion F is, for example, 8 mm, the stroke from the start of flange bending by the sectional die 4 to the position of the bottom dead center is distributed as shown in FIG.

As shown in FIG. 4, the insert punch 9 is once separated from the work W, and the plunger 13 of the oil breaker 12 is formed as the concave seat Q is formed.
Also gradually protrudes, and serves to prevent springback of the concave seat Q at this stage, that is, to prevent the concave seat Q from returning to its original state.

When the upper die 1 starts to rise again from the state shown in FIG. 1C and FIG. 4, the insert punch 9 attempts to return to the initial state together with the sectional die 4, so that the insert punch 9 becomes a hemming flange. The concave seat portion Q is corrected so that the concave seat portion Q is restored to its original state by contacting the tip of the portion F, and at the same time, the hemming flange portion F
Is bent so as to overlap the concave seat portion Q.

Thus, as shown in FIGS. 1D and 5, when the insert punch 9 returns to the state flush with the punch 6, the concave seat Q is completely restored to the original flat state. At the same time, the hemming flange portion F is completely folded back so as to be parallel to the portion which was the concave seat portion Q earlier, and the hemming process of the peripheral portion of the harness insertion hole H is completed.

As described above, according to the present embodiment, the upper die 1
Flange bending and pre-heming are performed until the bottom die reaches the bottom dead center position. On the other hand, in the process of returning the upper die 1 from the bottom dead center position to the initial state, hemming is performed to completely fold the hemming flange portion F. The harness insertion hole H
Can be completed in the hemming process of the peripheral portion of.

Here, it is needless to say that the present invention can achieve the initial object even when the arrangement of the upper and lower dies shown in the above embodiment is reversed upside down.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a series of steps showing a preferred embodiment of the present invention.

FIG. 2 is a view showing details of FIG. 1A, and is a cross-sectional view of a principal part showing a state where a pad presses and restrains a work.

FIG. 3 is a view showing details of FIG. 1 (B), and is a cross-sectional view of a main part showing a state where flange bending has been completed.

FIG. 4 is a view showing details of FIG. 1C and is a cross-sectional view of a main part showing a state where pre-hemming processing is completed.

FIG. 5 is a view showing details of FIG. 1D, and is a cross-sectional view of a main part showing a state in which hemming processing has been completed.

FIG. 6 is an explanatory view of a stroke of the press die shown in FIGS.

FIG. 7 is an essential part perspective view showing a front structure of an automobile including a hood ridge lower panel which is an example of a work to be processed;

FIG. 8 is an explanatory view showing a conventional curling method similar to hemming.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Upper mold 2 ... Lower mold 3 ... Upper holder 4 ... Sectional die 5 ... Pad 6 ... Punch 8 ... Elastic body 9 ... Insert punch 11 ... Stepped part W ... Food ridge lower panel (work) H ... Harness insertion hole F ... Hemming flange Q: concave seat

Claims (5)

[Claims] An annular insert punch elastically supported by a punch so as to be vertically movable, a die opposed to the insert punch, and a pad elastically supported by the die so as to be vertically movable. A method in which hemming is performed on a peripheral portion of a hole formed in advance, wherein a die outside a peripheral portion of a hole to be a hemming flange portion is pressed and constrained by a punch including an insert punch and a pad, and the die is held. By pressing the inside of the insert punch, bending the hole peripheral portion to the insert punch side to form a hemming flange portion, by pressing the die still to the insert punch side following the flange bending process, While temporarily separating the insert punch from the work, insert the insert In the pre-heming step of bending the bundled portion in the direction of movement of the insert punch to form a seat, and in the process of returning the insert punch to the initial state together with the die after the pre-hemming process, the hemming flange portion is seated. A hemming step of correcting the seat to its original state while bending so as to be superimposed on the hemming process. 2. The method according to claim 1, wherein in the pre-hemming step, an outer portion of the hemming flange is drawn in a moving direction of the die by a frictional force between the die and the hemming flange to form a seat. Hemming processing method. 3. In the pre-heming step, the stepped portion on the outer periphery of the die is engaged with the base of the hemming flange,
3. The hemming method according to claim 2, wherein an outer portion of the hemming flange is drawn in a moving direction of the die with the movement of the die to form a seat. 4. A hemming apparatus used in the hemming method according to claim 1, wherein an insert punch is supported by the punch via an elastic body so as to be vertically movable, and the punch and the insert punch are used to lower the insert punch. While the mold is formed, a sectional die that can be inscribed in the insert punch is fixed to the upper holder, and a pad is elastically supported by the upper holder so as to be able to move up and down. A hemming apparatus, wherein an upper die is formed by the pad and the pad. 5. A stepped portion which is engaged with a root portion of a hemming flange portion after flange bending is formed on an outer peripheral surface of the sectional die.
The hemming apparatus described in the above.