JP2002361338A - Chip-clogging preventive device of small diameter hole pressing die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent chip-clogging of a die for stamping a minute diameter hole at a metal sheet. SOLUTION: The small diameter hole pressing die 1 provides a cutting edge 11 and a back relief hole 12 connecting to the rear of the cutting edge. A difference 13 in level spreading toward the back relief hole is arranged at a connecting portion between the rear end of the cutting edge and the front end of the back relief hole, and the back relief hole is made to have a hole diameter having no reverse slope toward the difference in level to the rear end. Thus, the unevenness of the length of the cutting edge is prevented by absorbing a shaft gap between the cutting edge and back relief hole in the difference in level, and the cutting edge can obtain a shape capable of preventing the occurrence of chip clogging. Further, because the stamped chips loose a sliding support portion caused by the difference in level when pressed by the die, the drop of stamped chips becomes smooth in the back relief hole, and the probability of chip clogging is consequently reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for pressing small holes, and more particularly to a technology for preventing clogging of a press die.

[0002]

2. Description of the Related Art In various precision parts such as wristwatch mechanical parts, hard disk drives (HDDs), information equipment parts such as CD-ROM and MD drives, and parts for fuel injection in automobiles, the plate thickness is about a fraction of a millimeter. When a hole having a small diameter (about 0.35 to 0.14 mm) is formed by punching a metal material (brass, phosphor bronze, beryllium copper, stainless steel, etc.) by press working, clogging directly affects the quality of the product. In particular, in such processing, even when the waste does not actually become clogged, the processing accuracy is reduced only by the tendency.

FIG. 5 shows an example of a die shape in which clogging actually occurs. In this case, it is considered that the nonuniformity of the length L of the cutting edge portion a as shown in FIG. The non-uniformity of the cutting edge length L is mainly caused by the coaxiality between the hole wall surface b of the cutting edge portion a and the hole wall surface c of the back escape, and the smaller the taper of the back escape, the more likely it is to occur. Is also difficult.

Next, FIG. 6 shows an example in which the back escape shape has an inverse taper. In this example, for a blade having a cutting edge diameter P of 0.8 mm or less, a back relief taper of 1/150 to 1/300 is provided from the opposite side (the lower side in the figure) of the cutting edge by electric discharge machining. In the case of such electric discharge machining, the tip swings due to insufficient rigidity of the electrode, and an inverted tapered portion d is generated. Although this inverted taper is emphasized in the drawing, it is extremely fine and cannot be found unless the die is actually cut to see the cross section.

[0005]

As described above, the cause of clogging is very difficult to find, and it may be caused by a combination of a plurality of factors. In general, in addition to the non-uniformity of the cutting edge length L and the reverse taper d of the back relief shape, excessive cutting edge length, cutting edge reverse gradient, It is presumed that the cause is an inappropriate back escape shape, surface roughness, or the like.

Accordingly, a first object of the present invention is to provide a die shape in which the possibility of clogging is reduced by preventing non-uniform cutting edge lengths caused by the processing accuracy of the die.

[0007] By the way, not only clogging occurs due to the die itself, but also due to a backing plate or a die set on which the die is mounted. If the backing plate is the cause, it is estimated that the misalignment of the hole, improper setting of the hole diameter, roughness of the inner surface roughness of the hole, improper setting of waste collection, residual processing oil, etc. are the causes. In such a case, it is assumed that the cause is improper setting of the waste collection (small waste is often caught between large wastes) and residual processing oil.

Accordingly, it is a second object of the present invention to provide a waste jam prevention device capable of comprehensively preventing waste jam including the above-mentioned backing plate and die set.

[0009]

In order to achieve the first object, the present invention provides a small-diameter hole pressing die having a cutting edge and a back escape hole communicating with a rear end of the cutting edge. At the communicating portion between the rear end of the blade and the front end of the back escape hole, a step extending toward the back escape hole is provided, and the back escape hole has a hole diameter with no reverse gradient from the front end to the rear end. And

In the above-mentioned configuration, in order to obtain a back relief shape in which a reverse gradient hardly occurs due to a processing error, it is effective that the back relief hole is formed in a conical shape having a relief taper extending in a direction opposite to the cutting edge.

Next, in order to achieve the second object, the present invention includes a small-diameter hole press working die having a cutting blade and a back escape hole communicating with a rear end of the cutting blade. And a bypass hole for communicating the back escape hole to the atmosphere, and a rear end of the back escape hole is connected to a suction device.

In the above configuration, it is effective that the die has a notch on the outer periphery thereof, and the bypass hole is opened to the notch.

In the above configuration, it is effective that the rear end of the back escape hole is connected to a suction device via a waste accumulation tank.

In the above-mentioned configuration, in order to obtain a back escape shape in which a reverse gradient hardly occurs due to a processing error, it is effective that the back escape hole is formed in a conical shape having an escape taper extending in a direction opposite to the cutting edge.

[0015]

According to the first aspect of the present invention, the step provided at the connecting portion between the cutting edge and the back escape hole absorbs an unavoidable axis shift due to a processing error between the cutting edge and the back escape hole, and the cutting edge is provided. It functions to prevent the occurrence of uneven length. In addition, the step functions as an abruptly enlarged portion of the hole diameter when the scrap enters the back escape hole from the cutting edge during use, and acts so as to rapidly lose the sliding contact support surface of the scrap.

According to the second aspect of the present invention, by forming the back clearance hole into a conical shape having a clearance taper, it is possible to obtain a back clearance shape that does not easily cause a reverse gradient due to a processing error.

According to the third aspect of the present invention, since a flow path of a suction airflow from the back of the cutting blade to the suction device is formed in the back escape hole with the bypass hole as an inlet, the negative pressure is thereby reduced. Thus, a negative pressure can be generated in the cutting blade to promote the discharge of the waste.

Further, according to the configuration of the fourth aspect, the notch on the outer periphery of the die can function as a suction port of the bypass hole.

Further, in the structure according to the fifth aspect, the waste accumulation tank interposed between the rear end of the back clearance hole and the suction device functions as a space for rapidly expanding the cross-sectional area of the suction passage. The scum is separated from the suction airflow by its own weight due to the decrease in the flow velocity, and is collected at the bottom of the scum accumulation tank.

Further, in the configuration of the sixth aspect, the escape taper of the back escape hole functions to sequentially increase the flow path cross-sectional area of the suction airflow in the back escape hole in the downstream direction, thereby facilitating the discharge of waste. The flow velocity of the suction airflow can be increased immediately after the cutting edge.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of a small-diameter hole pressing die to which the present invention is applied. As shown in the figure, the die 1 is formed into a cylindrical shape as a whole, and has a cutting edge 11 formed of a circular hole formed at the front end (upper side in the figure).
And a back escape hole 12 which is also a circular hole and communicates with the rear end (the lower end in the figure) of the cutting blade 11. Cutting edge 1 of die 1
1 has a length of 2 to 3.5 times the pore diameter. A step 13 extending toward the back escape hole 12 is provided in a communicating portion between the rear end of the cutting blade 11 and the front end of the back escape hole 12. In order to make the back escape hole 12 have a hole diameter with no reverse gradient from the front end to the rear end, in this embodiment, it is possible to avoid a reverse gradient due to a manufacturing error, and to smoothly discharge waste by gravity. For this purpose, the shape is a frusto-conical shape having a relief taper of 1/50 or more.

The die 1 further has a bypass hole 14 for communicating the back escape hole 12 to the atmosphere. In the present embodiment, the bypass hole 14 is at 45 ° to 60 ° with respect to the axis of the back escape hole 12.
It is a hole with a circular cross section having an axis that intersects at an angle,
An opening is formed in the back escape hole 12 behind the cutting blade 11. In this embodiment, a part of the cylindrical peripheral surface is provided on the outer periphery of the die 1.
A notch 15 cut into an arcuate cross section when viewed from above is formed, and the inlet side of the bypass hole 14 is open to a plane portion of the notch 15. Further, the outlet side of the bypass hole 14 is opened immediately after the cutting blade 11 in order to increase the negative pressure generated in the cutting blade 11 as much as possible.

As shown in FIG. 2, the die 1 having such a configuration is placed on a lower die set 21 of a press machine via a backing plate 22 and fitted and fixed to a jig 23. A discharge hole 22 a having a diameter larger than the diameter of the rear end of the back escape hole 12 (see FIG. 1) is formed in the backing plate 22 so as to be aligned with the axis. A discharge hole having a diameter sufficiently larger than the hole 22a is formed, and a base 3 having a larger diameter than the discharge hole 22a is fitted and fixed to the discharge hole. The base 3 is connected to a waste accumulation tank 5 via a discharge pipe 4 connected to the rear end. The upper part of the waste accumulation tank 5 is connected via a suction pipe 6 to a suction device 7 constituted by a vacuum pump. Thus, the rear end of the back escape hole 12 is connected to the suction device 7 via the waste accumulation tank 5. Although not shown, a filter is interposed at the inlet or in the middle of the suction pipe 6 that connects the waste accumulation tank 5 and the suction device 7, and the fine waste sucked into the waste accumulation tank 5 and the oil mist are removed. Suction into the suction device 7 is prevented.

In the apparatus configured as described above, by operating the suction device 7 during press working, the back escape hole 12 (see FIG. 1) from the bypass hole 14, the discharge hole 22a of the backing plate 22, the base 3 In addition, a suction path extending to the discharge pipe 4 and the waste accumulation tank 5 is formed, and the inside of the cutting blade 11 is brought into a negative pressure state lower than the atmospheric pressure by drawing air in through the suction path. Therefore, in such a state, when the plate material is punched by the lowering of the punch fixed to the upper die (not shown), the scrap that is pushed by the tip of the punch and falls in the cutting blade 11 is caused by its own gravity and negative pressure. In addition, extremely fine scum generated by shearing due to punching is smoothly guided into the back escape hole 12 mainly by suction force due to negative pressure, and at this time, the scum loses the peripheral surface support at the step 13 part, and The fine scum falling in the escape hole 12 rides on the airflow of the suction path, descends as a scrap flow, and gradually increases in diameter to the discharge hole 22.
a, through the suction path passing through the base 3 and the discharge pipe 4, is guided to the waste accumulation tank 5.

Since the cut waste entering the waste accumulation tank 5 enters the waste accumulation tank 5 from the suction path, the cross-sectional area of the flow path is rapidly increased. It is accumulated below the accumulation tank. Also,
The very fine scum generated by the shearing caused by the punching may be sucked into the suction pipe 6 by the suction airflow, but is collected by the filter of the suction pipe 6 like the oil mist.

Thus, according to the apparatus of the first embodiment, the die 1 itself forms a step 13 connecting the cutting edge 11 and the back escape hole 12, and is clogged by the escape taper provided in the back escape hole 12. In addition to the difficult shape, the inside of the cutting blade 1 and the back escape hole 12 is in a negative pressure state, so that the processing oil mixed into the cutting blade 1 together with the scum is also discharged, and the processing oil passes through the processing oil. It is possible to prevent clogging due to sticking, and it is possible to smoothly discharge the clogging.

FIG. 3 is a sectional view showing a second embodiment in which the shape of the back escape hole is changed. In this embodiment, the back escape hole 12
Is formed in a cylindrical shape having a hole diameter of 2 to 3 times the cutting edge diameter P so as to sufficiently widen the gap with the peripheral surface of the falling scrap. Even in such a case, as in the case of the first embodiment, the waste enters the back escape hole 12 from the cutting edge 11 through the step 13 so that the support portion is lost due to a sudden increase in the hole diameter. A similar effect is achieved in that extremely fine scum does not easily adhere to the hole surface of the back escape hole 12.

In the case of this embodiment, when the die 1 itself is viewed, the diameter of the back escape hole must be larger than the diameter P of the cutting edge. It is unavoidable that the size of the back escape hole 12 is larger than that of the first embodiment in that the hole wall surface of the back escape hole 12 needs to be finished so as not to have a reduced diameter.
Since 2 is a straight hole, there is an advantage that the processing of the hole itself is simplified.

FIG. 4 is a sectional view showing a third embodiment in which the shape of the bypass hole 14 is changed. In this embodiment, the bypass holes 14 are a plurality of holes directly opening on the outer peripheral surface of the die 1. The fixing jig 23 of the die 1 has an introduction hole 23a communicating with the bypass hole 14.

In this case, the bypass hole 14
, A symmetrical suction airflow (indicated by an imaginary line with an arrow in the figure) is generated along the hole axis of the back escape hole 12, so that the effect of preventing the clogging is further improved. There is expected. It should be noted that, similarly to the first embodiment, a configuration in which each of the bypass holes 14 is opened to the atmosphere through the notch is also possible in the case where a plurality of bypass holes 14 are provided.

As described above, each characteristic point of the present invention has been described based on the embodiment embodied by a combination of conceivable and suitable forms. However, the present invention is not limited to the specific examples. Various specific configurations can be adopted within the scope of the matters described in the individual claims of the claims.

[0032]

According to the first aspect of the present invention, since the cutting edge and the back escape hole are connected via the step, the cutting edge and the back escape hole are connected at the step portion. Can be absorbed to prevent the cutting blade length from becoming uneven. Therefore, with this configuration, the cutting blade can be formed into a shape that is hardly clogged with debris. Also, at the time of press working with this die, since the cut waste enters the back escape hole through the step from the cutting blade, the sliding contact support part is lost due to the rapid expansion of the hole diameter,
The dropping of the scraps at the back escape hole becomes smooth, and accordingly, extremely fine waste generated by punching is discharged without adhering to the hole surface of the back escape hole, reducing the possibility of clogging Is done.

According to the second aspect of the present invention, it is possible to obtain a back relief shape in which a reverse slope due to a processing error is less likely to occur due to the clearance taper of the back clearance hole. Further, since the diameter of the back escape hole for the scrap is gradually increased in the discharge direction, the possibility of the back escape hole being caught on the wall surface of the back escape hole when the waste is discharged can be reduced.

According to the third aspect of the present invention, a flow path of a suction airflow from the back of the cutting blade to the suction device is formed in the back escape hole with the bypass hole as an inlet.
With this negative pressure, a negative pressure can be generated in the cutting blade that promotes the discharge of scum. Therefore, by generating a scrap flow in which the scum discharged to the back escape hole by the negative pressure in the cutting blade is put on the suction airflow to promote the discharge of the scum, it is possible to prevent the scum jam.

According to the configuration of the fourth aspect, it is not necessary to take any special means for suction in the jig holding the die when generating the scrap flow, so that the positioning of the die can be performed. And the setup for processing can be simplified.

Further, according to the configuration of the fifth aspect, since the scraps are collected at the bottom of the scrap accumulation tank, the amount of the scraps can be estimated by monitoring the amount of the scraps collected, and the scraps are actually jammed. Advance measures are easy,
Maintenance of product processing accuracy is facilitated.

Further, according to the structure of the sixth aspect, the flow velocity of the suction airflow formed in the back escape hole becomes large immediately after the cutting edge, so that the fine airflow which is particularly easy to ride on the airflow and has a small own weight is reduced. Emissions are promoted. Also, with this,
The discharge of the processing oil, which adheres to the fine residue and causes the clogging, is also promoted.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a small-diameter hole pressing die according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a device for preventing clogging using the die.

FIG. 3 is an axial sectional view of a small-diameter hole pressing die according to a second embodiment of the present invention.

FIG. 4 is an axial sectional view of a small-diameter hole pressing die according to a third embodiment of the present invention.

FIG. 5 is an axial sectional view showing an example of a conventional small-diameter hole pressing die.

FIG. 6 is an axial sectional view showing another example of a conventional small-diameter hole pressing die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Small-diameter hole press die 11 Cutting blade 12 Back escape hole 13 Step 14 Bypass hole 15 Notch 5 Scrap accumulation tank 7 Suction device

Claims (6)

[Claims] 1. A small-diameter hole pressing die having a cutting blade and a back clearance hole communicating with a rear end of the cutting blade, wherein a back clearance is provided at a communicating portion between a rear end of the cutting blade and a front end of the back clearance hole. A small-diameter hole-pressing die, characterized in that a step extending toward the hole side is provided, and the back escape hole has a hole diameter without a reverse slope from a front end to a rear end thereof. 2. The small-diameter hole press working die according to claim 1, wherein the back escape hole has a conical shape having an escape taper extending in a direction opposite to the cutting edge. 3. A small-diameter hole press die having a cutting blade and a back escape hole communicating with a rear end of the cutting blade, wherein the die has a bypass hole for communicating the back escape hole to the atmosphere. An apparatus for preventing clogging of a small-diameter hole press die, wherein a rear end of the back escape hole is connected to a suction device. 4. The small-diameter hole press die according to claim 3, wherein the die has a notch on an outer periphery thereof, and the bypass hole is opened in the notch. 5. The small-diameter hole press die according to claim 3, wherein a rear end of the back escape hole is connected to a suction device via a waste accumulation tank. 6. The back escape hole is formed in a conical shape having an escape taper extending in a direction opposite to the cutting edge.
A device for preventing clogging of a small-diameter hole pressing die according to the above description.