JP2530387Y2 - Burring mold - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burring die for burring or drawing a hole formed in an end face of a work.

[0002]

2. Description of the Related Art In a conventional burring mold using a cored bar punch having a thin peripheral edge at the tip end, since the inner periphery of the forming part of the forming die is cylindrical and there is a gap between the outer periphery of the work,
The peripheral edge of the core punch was easily broken. Further, the prior art relating to the burring mold is disclosed in
No. 152317, Japanese Utility Model Application Laid-Open No. Sho 61-205622, Japanese Utility Model Application Laid-open No. Sho 62-50823, etc., but could not solve the above-mentioned problems.

[0003]

In the mold according to the above-mentioned prior art shown in FIG. 3, an inner periphery 11a of a molding portion of a molding die 11 which is in contact with the outer periphery We of the work W and holds the outer periphery We of the work W is formed. Because of the cylindrical shape, a gap is formed between the outer periphery We of the work and the peripheral edge of the thin metal core punch 13 is pressed in the centrifugal direction by burring molding or drawing molding, and is crushed by cracks or the like or crushed by repeated stress. There was an easy problem. Further, it is difficult to perform the forming process with an appropriate pressure with the above-mentioned gap set to zero so as not to crush the metal core punch, because of the deviation of the outer diameter of the work.

The present invention has been made in view of these problems of the prior art, and an object thereof is to taper the inner periphery 11a of a forming portion of a forming die 11 so as to obtain a diagram in burring forming or drawing forming. As shown in FIGS. 1 and 2, the outer periphery We of the work is inscribed at an appropriate constant pressure at the inner periphery 1 a of the forming portion of the tapered die 1, and the core punch 3 is crushed even if the tip peripheral edge of the core punch 3 is pressed in the centrifugal direction. It is not necessary to minimize the gap between the outer diameter We of the work and the inner circumference 11a of the forming portion in the prior art, and it is intended to facilitate the die forming in the outer diameter forming step and the burring or drawing forming step. It is intended to provide a burring mold.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a burring mold according to the present invention has a tapered inner periphery of a forming part of a forming die which is inscribed in the outer periphery of a work and holds the outer periphery of the work. A vertically movable taper die, a burring punch that projects into a hole formed in the end of the work and projects the end face of the work, and presses and lowers the work while cooperating with the taper die and the burring punch. A metal core punch for forming the outer periphery of the projecting portion, a knockout for abutting against the end face of the workpiece to be lowered and cooperating with the metal core punch to raise the workpiece after molding, and a compression spring for urging the tapered die A pressing pin urged by a spring to raise the knockout, which is free to move up and down; and a die for holding the tapered die and defining a rising end and holding the compression spring. Holder and is made by a punch burying member to prevent the other end of the compression spring and fixed to the die holder with embedding the burring punch.

[0006]

The operation of the present invention having the above-mentioned means will be described with reference to FIGS. 1, 2 and 4, but the operations of burring and drawing are very similar. It is explained as follows. The tapered die 1 has a compression spring 5 that abuts on a lower end portion of the tapered die 1 having an upper edge inner diameter larger than the outer diameter of the work W and a lower edge inner diameter smaller than the outer diameter of the work W.
In the burring forming, the taper surface and the work W
Is lowered to a predetermined position where burring is formed after inscribed, and after burring is formed, it is raised to the rising end by the upward pressing of the knockout 4 which is raised by the pressing pin 6. The burring punch 2 includes a punch embedding member 8.
And is waiting at a predetermined position.

[0007] Then, the core metal punch 3 descends and fits the work W before burring molding transferred from the previous process, and the work W shown in FIG.
When the workpiece W approaches the upper end of the inner periphery 1a of the forming part of the tapered die 1, the work outer periphery We can be easily introduced into the inner periphery 1a of the forming part, so that the work W is further sandwiched between the metal core punch 3 and the knockout 4. While the core punch 3 descends, the outer periphery We of the work comes into contact with the inner periphery 1a of the forming part and continues to descend while pressing the taper die 1, and the core punch 3
The hole Wa formed in the end Wb of the workpiece W is guided to the pointed end 2a of the burring punch 2 waiting at a predetermined position by the downward pressing of the burring punch 2, and the outer peripheral portion 2 of the burring punch 2 is guided.
b is inserted through the hole Wa, and the end W is cooperated with the tapered die 1, the core punch 3 and the knockout 4.
When the burring is formed as shown in FIG. 4B in which b is projected into the inside of the work W, the lowering of the core punch 3 is stopped, and after the burring is completed, the core punch 3 is raised. Since the pressing pin 6 rises due to the pressing of the spring not to press the knockout 4, the workpiece W is raised by being sandwiched between the knockout 4 and the metal core punch 3.
The tapered die 1 is pressed by the compression spring 5 while being in contact with the outer periphery We of the work W, and the rising end is defined by the projecting portion of the upper edge of the die holder 7. Stipulated. While the core punch 3 continues to rise, the work W is clamped by fingers (not shown) and the rising end is defined by a stripper (not shown) on the way, so that the work W is separated from the core punch 3 and the work W is transferred by transfer means (not shown). Is transferred to the next step.

By the way, the inner circumference 1a of the tapered die 1
In an experiment in which the effective distance in the axial direction of the taper die 1 in a certain work was set to 5 mm, the difference between the inner diameter of the upper edge and the inner diameter of the lower edge was 0.02 to 0.10 mm (taper =
0.004 to 0.020, taper angle 0.22 to 1.1
4 °). For this reason, the inner peripheral surface 1a of the formed portion is formed by the vertical pressing force of the cored bar punch 3 shown in FIG.
Since the reaction force acting horizontally on the workpiece outer periphery We is 500 to 100 times the vertical pressing force in the experimental example, the reaction force acts to protect the metal core punch 3 via the work W during burring. I do. Further, according to the present invention, as apparent from the above-described results, drawing can be easily performed in addition to burring.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1 showing the initial stage of burring molding, FIG. 2 showing the final stage of burring molding, and FIG. 4 showing the form of a workpiece. Taper die 1
A small-diameter portion is provided at the upper portion of the outer periphery, and a large-diameter portion is provided at the lower portion of the outer periphery. The small-diameter hole and the large-diameter hole provided in the die holder 7 are respectively inscribed and held in a vertically movable manner. The outer periphery of the upper portion of the knockout 4 is circumscribed to the upper outer diameter of the knockout 4 to make it freely movable up and down. The compression spring 5 held by the punch embedding member 8 presses the lower end surface thereof and rises following the rise of the metal core punch 3. The rising end has a step provided on the outer peripheral portion at the upper edge of the die holder 7. Defined by the protrusions (FIG. 1),
The lower end is determined at a position where the workpiece outer periphery We descends while being in contact with the tapered surface provided on the inner periphery 1a of the forming part and the lowering of the cored bar punch 3 stops after the completion of burring forming (FIG. 2).

The burring punch 2 is provided with a large-diameter portion at the lower end, a small-diameter portion (2b in the figure) acting on the inner periphery Wf of burring at the center, and a tapered portion (2a in the figure) at the upper end. After being inserted through the large-diameter hole and the small-diameter hole provided in the embedding member 8 as shown in the figure, a locking portion including a large-diameter portion at the lower end provided in the burring punch 2 and a large-diameter hole provided in the punch embedding member 8 is used. The burring punch 2 is embedded and held by a punch embedding member 8.

The metal core punch 3 is held by a punch holder (not shown) attached to a ram of a press (not shown) at the upper portion, and moves up and down (up and down) via the punch holder by up and down movement of the ram of the press. The outer periphery is fitted with the inner periphery Wd of the work W so that the work W can be transported up and down, a forming hole adapted to the outer periphery Wg of the burring forming portion is provided at the lower end entrance, and a burring punch is provided deep inside the lower end. A vertical air hole for removing air when the burring punch 2 is inserted into the guide hole, and horizontal air penetrating from the vertical air hole to the outer periphery of the cored bar punch 3 at the deepest inside of the lower end. Holes are provided to facilitate burring molding.

The knockout 4 is provided with a tapered small-diameter portion of the tapered die forming portion inner periphery 1a and a small-diameter portion slidable at the upper portion of the outer periphery, and a large-diameter portion which does not interfere with the inner diameter of the compression spring 5 at the lower portion of the outer periphery. Small diameter part of burring punch 2 (2 in the figure)
b) and a guide hole which is slidable is provided so as to freely move up and down.
The lower end of the knockout 4 is pressed by the upper end surfaces of the plurality of pressing pins 6 raised by a spring (not shown), and the lower surface of the knockout 4 is pressed by the spring (not shown). As shown in FIG. 1, the rising end is defined by the contact between the outer peripheral step and the lower surface of the tapered die 1.
The lower end is defined by abutting the upper end of the punch embedding member 8 with the lower end of the large diameter portion as shown in FIG.

The compression spring 5 has an outer periphery loosely engaged with and held by the die holder 7 and the punch embedding member 8, an inner periphery formed so as not to interfere with the knockout 4 and the plurality of pressing pins 6, and a lower end surface having the punch embedded therein. It is inserted into a circular recess provided on the upper surface of the member 8 and receives one of the spring pressures on the lower surface of the circular recess, and the upper end surface is constantly in contact with the tapered die 1 to press the tapered die 1. The spring pressure of the compression spring 5 is 1
a is pre-compressed to the spring pressure required to apply an appropriate compressive force to the metal core punch 3 via the work W while inscribed in the workpiece outer periphery We, and follows the rise of the metal core punch 3 after burring forming. Then, the taper die 1 is pressed and raised.

Each of the plurality of pressing pins 6 is constantly pressed upward by a spring (not shown), and is freely slidably inserted into a guide hole formed in the lower base 9 and the punch embedding member 8 so that the upper end surface is the lower end surface of the knockout 4. During the burring process, the lower surface of the knockout 4 is lowered while the upper surface of the knockout 4 is in contact with the work forming end portion Wb.
The knockout 4 is pressed and raised following the rise of the knockout.

The die holder 7 has a tapered die 1 on the lower inner periphery.
And a large-diameter portion surrounding the compression spring 5 so that the compression spring 5 can freely move up and down, a small-diameter portion protruding in the upper inner periphery and provided on the upper outer periphery of the tapered die 1, and a small-diameter portion slidably provided. The rising end of the tapered die 1 is fixed to the punch embedding member 8 by a step provided between the large diameter portion and the small diameter portion.

The punch embedding member 8 is provided with a large-diameter hole for holding the burring punch 2 below the shaft center portion and a small-diameter hole for passing the small-diameter portion of the burring punch 2 above the shaft center portion. A plurality of holes for inserting a plurality of pressing pins 6 are provided around the provided large-diameter hole and small-diameter hole, and a compression spring 5 is inserted around the insertion holes of the plurality of pressing pins 6 on the upper surface. A concave portion is provided, and the upper end surface is fixed to the die holder 7 and the lower end surface is fixed to the well-known lower base 9, respectively. Although the embodiment of the burring molding has been described above, the drawing can be performed with the same configuration as the above in the drawing.

[0017]

[Effects of the Invention] The present invention is configured as described above, and has the following effects. Inner circumference 1 of forming part of taper die 1
a is formed into a taper, so that the outer periphery We of the work is formed by the inner periphery 1a of the formed portion during burring or drawing.
Since burring or drawing is performed while reducing the stress acting on the peripheral edge of the core punch 3, the life of the core punch 3 is extremely long, and the cost of the burring die can be reduced. . Further, as described above, the frequency of mold replacement due to the crushing of the metal core punch 3 is reduced, so that the work efficiency is improved. Further, the above-mentioned process facilitates burring or drawing of a thick work plate, which was impossible with the conventional technique.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold part showing an initial stage of burring molding.

FIG. 2 is a sectional view of a mold part showing a final stage of burring molding.

FIG. 3 is a sectional view of a mold part showing burring molding according to a conventional technique.

FIG. 4 is a cross-sectional view showing an example before and after burring molding of a work.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Taper die 2 Burring punch 3 Core punch 4 Knockout 5 Compression spring 6 Press pin 7 Die holder W Work

Claims (1)

(57) [Scope of request for utility model registration] In a burring molding die having a small difference between an inner diameter of a work and an outer diameter of a desired burring forming portion, an inner periphery of a forming die of a forming die which is in contact with an outer periphery of the work and holds the outer periphery of the work. , A burring punch that projects into a hole formed in the end of the work and projects the end face of the work, a taper die that presses and lowers the work, and the taper die and the burring punch. A core metal punch that forms the outer periphery of the protruding portion in cooperation with a compression spring that urges the tapered die, a die holder that holds the tapered die and defines a rising end, and that holds the compression spring. A burring mold that can be drawn.