JPH0670919U - Burring mold - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a robust mold for burring molding in which the difference between the inner diameter of the work and the outer diameter of the burring molding portion is small. [Structure] The inner circumference 1a of the molding portion of the taper die 1 urged by a compression spring 5 that abuts on the lower end surface is tapered and held vertically by a die holder 7, and is buried concentrically with the taper die 1 to stand by by burring. A burring punch 2 for forming the inner circumference Wf of the portion is provided, and concentric with the taper die 1, it is attached to a ram of a press and held by a punch holder and lowered by the ram to fit the work W and burring or Providing a core metal punch 3 that performs drawing,
A die for burring, characterized in that the above-mentioned molding is performed by reducing the stress acting on the peripheral portion of the tip of the core metal punch.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a burring mold for burring or squeezing a hole formed in an end surface of a work.

[0002]

[Prior art]

 In a conventional burring die that uses a core bar punch with a thin tip peripheral edge, 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 piece and the peripheral edge of the core bar punch, Was easily crushed. Further, prior arts relating to burring molds are disclosed in Japanese Utility Model Publication No. 61-152317, Japanese Utility Model Publication No. 61-205622, Japanese Utility Model Publication No. 62-50823, etc., but the above problems are solved. It wasn't possible.

[0003]

[Problems to be solved by the device]

 In the mold according to the above-described conventional technique shown in FIG. 3, since the inner periphery 11a of the forming portion of the forming 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 has a cylindrical shape, There is a problem in that there is a gap between them, and the thin-walled peripheral edge of the core bar punch 13 is pressed in the centrifugal direction by burring molding or drawing, and is crushed by cracks or crushed by repeated stress. Further, in order to prevent the core metal punch from being crushed, it is difficult to perform the forming process with an appropriate pressure with the above-mentioned gap being zero 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 make the inner periphery 11a of the molding portion of the molding die 11 a taper and to perform burring molding or drawing molding. 1 and FIG. 2, the outer circumference We of the work is inscribed in the inner circumference 1a of the forming portion of the taper die 1 at a constant pressure at appropriate times, and the core metal punch 3 is broken even if the tip peripheral edge portion of the core metal punch 3 is pressed in the centrifugal direction. The purpose of the present invention is to prevent crushing and to facilitate the die manufacturing of the outer diameter forming step and the burring or draw forming step without the need to minimize the gap between the work outer diameter We and the forming portion inner circumference 11a in the prior art. It is intended to provide a die for burring.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the burring mold of the present invention comprises a taper die that is in contact with the outer circumference of a work and holds the outer circumference of the work by tapering the inner circumference of the forming part of the forming die, A burring punch that protrudes into the hole formed in the end of the work to project the end surface of the work, and presses and lowers the work, and cooperates with the taper die and the burring punch to adjust the outer circumference of the projection. A core bar punch for forming, a knockout for abutting the end face of the lowered work to raise the work in cooperation with the core bar after forming, a compression spring for urging the taper die, and a spring. Pressure pin that is urged to rise the knockout that can move up and down freely, a die holder that holds the taper die and defines the rising end, and holds the compression spring, and It is made and a punch burying member to prevent the other end of the compression spring and fixed to the die holder with burying Gupanchi.

[0006]

[Action]

 The operation of the present invention having the above-mentioned means will be described with reference to FIGS. 1, 2 and 4, but since the operations of burring molding and drawing are very similar, the operation in burring molding will be described as follows. To do. The taper die 1 has a taper in which the inner diameter of the inner periphery 1a of the forming portion is larger than the outer diameter of the work W and the inner diameter of the lower edge of the other is smaller than the outer diameter of the work W, and the compression spring 5 that abuts on the lower end portion When the burring is performed, the taper surface and the outer circumference We of the work W are lowered by the downward pressing of the core metal punch 3 to a predetermined position for the burring forming after inscribed. The knockout 4 is pushed up by the push pin 6 and is pushed up to the rising end. The burring punch 2 is embedded and held in the punch embedding member 8 and stands by at a predetermined position.

When the core metal punch 3 descends and the work W before burring molding transferred from the previous step is fitted and approaches the upper end of the inner circumference 1a of the molding part of the taper die 1 shown in FIG. Since the work outer circumference We can be easily introduced into the forming portion inner circumference 1a, the work piece outer circumference We is held in the forming portion while the work piece W is held by the mandrel punch 3 and the knockout 4. The taper die 1 is abutted against the circumference 1a and is continuously lowered while pressing the taper die 1, and the tip 2a of the barring punch 2 waiting at a predetermined position by the downward pressing of the core bar punch 3 is drilled at the end Wb of the work W. The punched hole Wa is guided, and the outer peripheral portion 2b of the burring punch 2 is inserted through the punched hole Wa and cooperates with the taper die 1, the core bar punch 3 and the knockout 4 to work the end portion Wb. Ku When the burring is formed as shown in FIG. 4 (B) so that it protrudes to the inside of W, the descending of the core bar punch 3 is stopped, and after the burring forming is completed, the core bar punch 3 is raised. The pressing pin 6 is lifted by the pressing of and the workout W is held by the knockout 4 and the core metal punch 3, and the work W is raised, while the taper die 1 is inscribed in the outer circumference We of the work W. Since the rising end is defined by the protrusion of the upper edge of the die holder 7 which is pressed by the compression spring 5, the ascending knockout 4 is also defined by the lower surface of the taper die 1. The core punch 3 continues to rise, but the work W is held by fingers (not shown) in the middle of the process, and the rising end of the work W is defined by a stripper (not shown). Therefore, the work W is separated from the core punch 3 and the work W is transferred (not shown). It is transferred to the next step by means.

By the way, the optimum taper amount of the inner circumference 1a of the forming portion of the taper die 1 is the difference between the inner diameter of the upper edge portion and the inner diameter of the lower edge portion in the experiment in which the effective distance in the axial direction of the taper die 1 in a certain work is set to 5 mm. Good results were obtained at 0.02 to 0.10 mm (taper = 0.004 to 0.020, taper angle ≈ 0.22 to 1.14 °). For this reason, the reaction force that acts horizontally from the inner circumference 1a of the forming portion on the work outer circumference We by the vertical pressing force of the core metal punch 3 shown in FIG. 2 is 500 to 100 times the vertical pressing force in the experimental example, so that burring During molding, this reaction force acts to protect the core bar punch 3 via the work W. Further, according to the present invention, as apparent from the above-mentioned results, it is possible to easily perform the draw forming in addition to the burring forming.

[0009]

【Example】

 An embodiment of the present invention will be described with reference to FIG. 1, which shows the initial stage of burring forming, FIG. 2 which shows the final stage of burring forming, and FIG. 4 which shows the form of a work. The taper die 1 is provided with a small-diameter portion on the upper outer periphery and a large-diameter portion on the lower outer periphery, respectively. The small-diameter hole and the large-diameter hole provided in the die holder 7 are inscribed so as to be vertically movable, and the inner periphery 1a of the formed portion is formed. Is provided with a taper described in the above-mentioned section of action and is circumscribed to the outer diameter of the upper part of the knockout 4 so as to be vertically movable, and by the lowering of the core metal punch 3, the inner periphery 1a of the forming portion is pressed down via the work W and is lowered. The lower end surface is pressed by the compression spring 5 held by the die holder 7 and the punch embedding member 8 and moves up following the rising of the core punch 3, and the rising end has a stepped portion provided on the outer peripheral portion of the die holder 7. It is defined by the projecting part of the upper edge (Fig. 1), and the descending end descends while the workpiece outer periphery We is inscribed on the tapered surface provided on the inner periphery 1a of the forming part, and the descending of the core metal punch 3 is stationary after the completion of burring forming. It is decided by the position ( 2).

The burring punch 2 has a large diameter portion at the lower end, a small diameter portion (2b in the figure) to be used for the inner circumference Wf of the burring molding at the center portion, and a taper portion (2a in the figure) at the upper end portion. After being inserted into the large-diameter hole and the small-diameter hole provided in the punch embedding member 8 as shown in the drawing, the retaining portion including the large-diameter portion at the lower end provided in the burring punch 2 and the large-diameter hole provided in the punch embedding member 8 The burring punch 2 is held in the punch embedding member 8 and embedded therein.

The core metal punch 3 is held by a punch holder (not shown) attached to the ram of a press (not shown) at its upper portion, and moves vertically (up and down) through the punch holder by the vertical movement of the ram of the press. The outer circumference of the work W is fitted with the inner circumference Wd of the work W so that the work W can be transferred up and down. A forming hole is provided at the lower end inlet to match the outer circumference Wg of the burring forming part. A guide hole for guiding the burring punch 2 is provided, and a vertical air hole for evacuating the burring punch 2 when the burring punch 2 is inserted into the guide hole is formed inside the lowermost end and the vertical air hole penetrates the outer circumference of the core bar punch 3. Established horizontal air holes to facilitate burring molding.

The knockout 4 has a small diameter portion which is slidable with the taper small diameter portion of the taper die molding portion inner circumference 1a on the outer peripheral portion, and a large diameter portion which does not interfere with the inner diameter of the compression spring 5 on the lower outer peripheral portion, and which is provided on the inner periphery. A small diameter portion (2b in the figure) of the burring punch 2 and a guide hole that can slide freely are provided to allow vertical movement, and the lower end of the core metal punch 3 abuts the workpiece end surface Wc on the upper end surface of the small diameter portion so that the upper end surface of the small diameter portion moves. The lower surface of the knockout 4 is pressed by the upper end surfaces of the plurality of pressing pins 6 which are pressed and lowered by a spring (not shown), and the cored bar punch 3 is moved upward and the rising end thereof is shown in FIG. As shown in FIG. 2, the outer peripheral step portion and the lower surface of the taper die 1 are contacted and defined, and the descending end thereof is defined by the lower end of the large diameter portion and the upper surface of the punch embedding member 8 contacting each other as shown in FIG.

The compression spring 5 has an outer circumference loosely held by the die holder 7 and the punch embedding member 8, an inner circumference formed so as not to interfere with the knockout 4 and the plurality of pressing pins 6, and a lower end surface thereof is punched. The embedded member 8 is inserted into a circular recess provided on the upper surface, and one side of the spring pressure is received by the lower surface of the circular recess, and the upper end surface is constantly in contact with the taper die 1 to press the taper die 1. The spring pressure of the compression spring 5 is pre-compressed to the spring pressure required to apply an appropriate compression force to the core metal punch 3 via the work W while the inner circumference 1a of the taper die forming portion is inscribed with the work outer circumference We, and the burring molding is performed. After that, the taper die 1 is pressed and raised in accordance with the rise of the core metal punch 3.

Each of the plurality of pressing pins 6 is constantly pressed upward by a spring (not shown), and is freely slidably inserted into the lower base 9 and the guide hole formed in the punch embedding member 8, and the upper end surface of the knockout 4 is inserted. When the burring is performed, the knockout 4 is pressed down while following the ascent of the core metal punch 3 after the burring. To raise.

The die holder 7 is freely slidable on a large diameter portion that surrounds the taper die 1 and the compression spring 5 by freely moving up and down in the lower inner circumference and a small diameter portion that protrudes in the upper inner circumference and is provided on the upper outer circumference of the taper die 1. A small diameter portion is provided, and the lower end surface thereof is fixed to the punch embedding member 8, and the rising end of the taper die 1 is defined by the step portion provided between the large diameter portion and the small diameter portion.

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

[0017]

[Effect of device]

 Since the present invention is configured as described above, it has the following effects. Since the inner periphery 1a of the forming portion of the taper die 1 is formed into a taper, the outer periphery We of the work is held at the inner periphery 1a of the forming portion at the time of burring forming or draw forming, and acts on the peripheral edge portion of the tip of the cored bar punch 3. Since the stress is reduced and the burring molding or drawing is performed, the life of the core bar punch 3 is extremely long, and the cost of the burring die can be reduced. Further, as described above, the frequency of die replacement due to the crushing of the core bar punch 3 is reduced, so that the work efficiency is improved. In addition, the above-described method facilitates the burring or drawing of a thick work plate, which has been impossible with the conventional techniques.

[Brief description of drawings]

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

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

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

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

[Explanation of symbols]

 1 Taper Die 2 Burring Punch 3 Core Bar Punch 4 Knockout 5 Compression Spring 6 Pressing Pin 7 Die Holder W Work

Claims (1)

[Scope of utility model registration request] 1. A burring molding die having a small difference between the inner diameter of the work and the desired outer diameter of the burring molding portion. In the burring molding die, the inner circumference of the molding portion of the molding die is in contact with the outer circumference of the work and holds the outer circumference of the work. A vertically movable taper die, a burring punch that projects into the hole formed at the end of the work to project the end surface of the work, and the taper die and the burring punch that press and lower the work. Burring molding provided with a core metal punch that cooperates with the core to form the outer periphery of the protrusion, a compression spring that biases the taper die, and a die holder that holds the taper die and defines the rising end and holds the compression spring. A burring mold that can be drawn.