KR920010606B1 - Drilling machine - Google Patents

Abstract

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Description

Pusher foot for printed board punch

Figure 1 is a side cross-sectional view showing a printed substrate punched pore pusher foot according to an embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II of FIG.

3 is a cross-sectional view taken along the line III-III of FIG.

4 is a bottom view showing the operation of the pusher foot shown in FIG.

FIG. 5 is an enlarged bottom view of the drill illustrating the relationship between the drill and air flow shown in FIG.

6 is a diagram showing the relationship between the drilling stroke and the machining time in the comparison between the pusher foot shown in FIG. 1 and the conventional pusher foot.

7 is a graph showing the relationship between cooling air temperature and air flow.

8 is a graph showing the relationship between drill wear and machined holes.

9 is a perspective view showing a printed circuit board puncturer.

10 is a side cross-sectional view showing a spin protrusion.

11 and 12 are exemplary views showing a conventional pusher foot.

The present invention relates to a printed circuit board puncturer, and more particularly to a pusher foot for a printed circuit board puncturer using a drill bit.

For example, Japanese Patent Application Laid-Open No. 61-124313 shows a pusher foot for a printed circuit board puncher for punching for a printed circuit board.

9 is an embodiment of a printed circuit board puncturer consisting of a bed 2 and a table 2 driven by driving means (not shown) and operatively supported on the bed 1. The drill 3 is prepared in a holder fixed to the table 2. A column 5 is provided on the bed 1 to support the table 2 with both legs. The spindle carriage 6 is operatively supported on the column 5 and is driven by the action of the Y-axis drive motor 7. The spindle saddle 8 is operatively supported on the spindle carriage 6 and is driven by the action of the Z-axis drive motor 9. Each rotor shaft 10 is supported on the spindle saddle 8 and rotates under the action of the motor 11. The pusher foot 12 is mounted on the cylinder block 13. Reference letter W denotes a printed circuit board (hereinafter simply referred to as a substrate). The substrate W is fixed on the table 2 by the standard pin P.

In this apparatus, the table 2 and the spindle carriage 6 are moved relative to each other in the X-Y direction to position the substrate W and the rotational shaft 10. The spindle then moves in the Z direction and drills with a drill supported on the associated rotor shaft 10.

10 shows the structure of the spindle portion of the printed circuit board puncher. In FIG. 12, the cylinder block 13 is fixed on the spindle saddle 8. A large diameter hole 14 and a flange 15 protruding radially inward from one end of the hole 14 are formed on the cylinder 13. The hole 14 is in fluid communication with the pressurized air source through the pipe 16.

The spindle 17 is fitted in the cylinder block 13 and is adapted to rotationally support the rotor shaft 10. The motor 11 is supported at one end of the spindle and is paired with the rotor shaft 10. The chuck 18 is fixed to the lower end of the rotor shaft 10 and then secures the drill 3. The piston or ram 19 has a flange 21 for actuation in a space defined by the cylinder block 13 and the holes 14 of the spindle 17.

The pusher foot 12 is fixed to one end of the piston 19. A suction port 22 connected to a vacuum suction source (not shown) is formed on the sidewall of the pusher foot 12. Grooves 23 are formed on the bottom wall of the pusher foot 12 to suck air during drilling.

This structure is supplied from the pipe 16 with compressed air maintained at a predetermined pressure to operate in the pipe 16 toward the lower end of the cylinder block 13. On the other hand, the air is discharged from the pusher foot 12 through the suction port 22. At this time, air is sucked through the opening formed in the lower end of the pusher foot 12 and discharged through the suction port 22 as shown in FIG.

In this condition, when the spindle saddle 8 shown in FIG. 9 is lowered, the pusher foot once supports the substrate W as shown in FIG. Thereafter, the drill 3 is pressed into the substrate W to punch.

In this case, the air is sucked into the pusher foot 12 through the groove 23 and then discharged through the suction port 22. The chips cut at the flow rate of the air sucked through the grooves 23 and the openings of the pusher foot 12 can be discharged and the drill 3 can be cooled.

Generally, dust collectors are used to collect chips cut with vacuum suction sources. The pressure in the pusher foot 12 during drilling is about 200 mm Hg.

In such a conventional apparatus, perforation is performed while the printed circuit board W is supported by the pusher foot 12, thereby preventing lifting and vibration of the printed circuit board during the drilling, thereby making high-quality drilling and simultaneously drilling. Damage to (3) can be prevented.

On the other hand, the cutting chip or powder generated during the drilling is collected in the dust collector.

However, since the groove 23 of the pressure foot is small in size, it is impossible to sufficiently secure the air flow rate during the drilling, and the drill 3 cannot be sufficiently cooled, and only the cutting chips or powder can be removed.

In particular, when cutting a small diameter of less than 1mm the cutting chip blocks the groove of the drill, it is difficult to discharge the cutting chip. For this reason, when it is necessary to have a large ratio of the hole diameter to the depth, the thrust load and the radial load applied to the drill 3 during drilling are increased, so that breakage due to bending or torsion is likely to occur.

In addition, when the groove for the drill 3 is blocked by the cutting chip, not only the cooling effect of the drill 3 is worsened, but also the amount of heat generated by friction between the chip and the inner wall of the hole increases, so that the temperature of the drill 3 increases considerably. do. And since the air at room temperature simply sticks to the drill 3, the temperature of the drill 3 is not sufficiently reduced, the wear of the drill 3 is remarkable, and the surface roughness of the inner wall of the perforated hole is increased, There are various problems, such as the occurrence of burrs at the exit and the increase of stains.

Furthermore, a portion of the cutting chip generated during drilling remains as a burr at the circumferential end of the hole, or else it is once attached to the inner wall of the drill and the pusher foot and then falls on the printed circuit board.

If the perforations of the printed circuit board are carried out under the condition that the chips remaining on the printed circuit board enter the space between the pusher foot and the circuit board, the quality of the inner wall of the perforated hole is degraded due to the vibration or lifting of the board. At the same time, the drill is prone to damage.

Accordingly, an object of the present invention is to reduce the puncturing stroke, shorten the puncture time, sufficiently cool the drill, and perform the removal of chips without fault. To provide a foot.

According to the present invention, in a pusher foot for punching machine, which is operatively supported in the axial direction of the spindle and is connected to the vacuum suction source and is suitable for fixing the printed circuit board for puncturing, the first air passage is A first supply port formed on the contact surface of the pusher foot with the printed circuit board at the first supply port formed on the side wall of the pusher foot, the first supply port being connected to the pressurized air source, and the second air passage being the side wall And a second air passage extending from the second supply port formed in the second supply port to the inside of the pusher foot, wherein the second air passage communicates with the supply source of pressurized air.

According to an aspect of the present invention, a first air passage extending to a first vent formed on a contact surface of a pusher foot having a printed circuit board and a second air passage extending to a plurality of second vents opened toward the inside of the pusher foot. Is formed on a pad fixed to the bottom of the pusher foot.

Further, the second vent is directed tangentially to the outer circumference of the drill supported by the spindle.

Furthermore, the nozzle with the opiris is formed in the second air passage.

At that time, the pressurized air is supplied to the first and second supply ports formed on the side wall of the pusher foot in the pressurized air source, and the pusher foot is operated toward the printed circuit board. As a result, the pressurized air is blown out of the first vent port against the contact surface of the pusher foot with the contact plate lying on the uppermost layer of the printed circuit board. A thin air film formed between the bottom surface and the contact surface of the pusher foot serves as an air bearing mechanism. The bottom surface of the pusher foot presses down the contact surface through the thin air film, and the printed circuit board is pressed and fixed by the bottom surface of the contact plate and the pusher foot.

The punching is performed on the printed circuit board under the condition that pressurized air is supplied from the pressurized air source to the second supply port formed on the sidewall of the pusher foot. As a result, the chip attached to the drill is blown out by the pressure of the pressurized air ejected from the second vent opening opened toward the inside of the pusher foot through the second supply port. The blown out chip is discharged together with the pressurized air ejected through the second vent because air sucked through the groove is discharged from the suction port during drilling and discharged into the pusher foot.

Under the condition that pressurized air from the pressurized air source is supplied from the first supply port formed in the side wall of the pusher foot, the pusher foot is operated toward the printed circuit board. The bottom surface of the pusher foot then pushes the contact surface downward through the air membrane. When the printed circuit board is pressed in place by the contact plate and the bottom of the pusher foot, the air of the pusher foot is sucked through the inlet. As a result, the inside of the pusher foot is maintained at a vacuum pressure. In a plurality of second vents passing through the second gas passage connected to the pressurized air source and open toward the lower inside of the pusher foot, the pressurized air is rapidly expanded (thermally expanded) to the second passage. It becomes low temperature inside. Cold air is blown along with the drill groove towards the drill to increase chip removal and drill cooling efficiency.

Therefore, it is possible to press down the printed circuit board, improve the processing hole, and prevent damage to the drill.

Embodiments of the present invention will now be described.

1 to 5 show a pusher foot for a printed circuit board puncher according to an embodiment of the present invention.

In FIG. 1, the spindle is adapted to rotationally support the rotor shaft 10 therein. The chuck 18 is fixed to the rotor shaft 10 to support the drill 3.

The pusher foot 12 is operatively assembled to the spindle 17. An inlet 22 for discharging air and chips in the pusher foot 12 is formed on the side wall of the pusher foot 12 and is connected to a dust collector (not shown) through a hose or the like. As shown in FIG. 2, the annular passage 12 is formed in the center of the lower end of the pusher foot 12 and extends radially outward toward the outer wall of the pusher foot 12 in the first air passage 25. Connected. The first supply port 26 is connected to the first gas passage 25. A second feed port 27 extending from the side wall of the pusher foot 12 is formed at the lower end of the pusher foot 12 as best shown in FIG. The second air passage 28 extends radially inward from the second supply port 27 toward the center. As shown in FIG. 1, the second air passage 28 is formed in an L shape toward the lower end face of the pusher foot 12 and is opened at the lower end face of the pusher foot 12.

As best shown in FIG. 4, the pusher foot 12 and the coupling pad 29 are fixed to the bottom surface of the pusher foot 12 at the coupling part 30. As shown in FIG. 3, a plurality of communication paths 31 extending radially in a predetermined length and connected to the first air passage 25 are formed in the pad 29. As shown in FIG. The first vent holes 32 are formed in each of the plurality of communication paths 31 and open at the bottom surface of the pad 29 (in the embodiment, two first vent holes are formed). As shown in FIG. 3, the annular passage 33 is formed at the center of the pad 29. A passage 34 having a predetermined length toward the outer wall of the pad 29 is connected to the annular passage 33. A nozzle 46 such as an orifice is formed in the passage 34.

The first air passage is composed of an annular passage 24, a first air passage 25, and a communication passage 31. In addition, the second air passage is composed of a second air passage 28, an annular passage 33 and a passage 34.

The second vent 35 is formed to open toward the inner wall of the lower end of the pusher foot 12. As shown in FIG. 5, the second vent 25 is cut so as to stick air to the drill 3 in accordance with the drill groove as seen from the drill tip.

Meanwhile, the adjustable high pressure air supply means 36 adjusts the pressure of the pressurized air for each of the two supply ports 26 and 27 to supply the pressurized air to the first supply port 26 and the second supply port 27. It is used to When the pressurized air 38 is supplied to the first supply port 26 when supporting the printed circuit board 37 during drilling, the first air passage 25, the annular passage 24, and the communication passage 31 are pressurized. Then, the pressurized air 38 is blown off from the first vent 32. As a result, a thin air film is formed between the contact plate 39 and the foot 12 raised on the uppermost printed circuit board 37. The thin air film acts as an air bearing, and pressurizes and supports the printed circuit board 37 by applying the depressurizing force of the pressurizing foot 12 to the contact plate 39 through the air film. Number 40 indicates the bottom plate.

The number 41 designates the cylinder block of the spindle saddle (see FIG. 1). Number 42 indicates the ram or piston of the pusher foot 12, and number 43 indicates the supply plate for the cylinder air. When air 44 is supplied into the cylinder block 41, the pressure is increased in the common container 45 to operate the pusher foot 12 in the Z direction (see FIG. 1).

A predetermined amount of pressurized air is regulated in the adjustable flow rate high pressure air supply means 36 to cool the drill during drilling and to remove cutting fragments or chips, and pressurized air is supplied to the second supply port 27 to provide a second Guided to nozzle 46 through air passage 28 and passage 34. The air is adiabaticly expanded by the nozzle 46 and the temperature is lowered through the passage 33. And air is blown against the drill 3 in a direction coinciding with the drill groove at the tip of the drill through the second vent hole 35 to cool the drill 3 and remove the cutting chips as shown in FIG. . Air in the pusher foot 12 is maintained at the vacuum level by the outlet 22. As a result, the cutting chip removed from the tip of the drill 3 is guided into the pusher foot 12 by the pressurized air blown out of the second vent hole 35 and the suction port together with the pressurized air introduced into the pusher foot 12. Discharged at 22 and blown out at the second vent 35. Reference numerals 47 and 48 denote O-rings for preventing air leakage. Reference numeral 49 denotes a hole formed in the substrate.

When the pressurized air is blown out of the second vent hole 35 in the direction indicated by arrow C of FIG. 1, the air flow indicated by arrows C, D, and E is generated as shown in FIG. The air is discharged.

Under this condition, when the spindle saddle 8 is lowered, the lower end face of the pusher foot 12 (ie the lower face of the paddle 29) is first contacted with the high contact plate 39 on the best printed circuit board 37. The contact plate 39 is cut off from the surrounding air and maintained at a vacuum pressure. As a result, the pressurized air supplied from the second supply port 27 is guided to the nozzle 46 through the second air passage 28 and the passage 34 and adiabaticly expanded through the nozzle 46. The temperature of the air is reduced in the passage 33 and is blown against the tip of the drill 3 in the direction along the drill groove as shown in FIG. 5 so that the second vent 35 and the pusher foot 12 The air suddenly expands within. At this time, the heating air 38 supplied from the first supply port 26 at the lower end surface of the pusher foot 12 (that is, the lower surface of the pad 29) is maintained at a high pressure and is ejected through the vent 32. An air film is formed between the lower end surface of the pusher foot 12 and the contact plate 39.

Furthermore, the spindle 17 is lowered as shown in FIG. 1 and the drill 3 is pressed down into the circuit board W to drill a hole. In this case, the air blown from the second vent 35 causes a flow as indicated by arrows C, D, and E of FIG. 1 to carry chips discharged from the substrate W and to cool the drill 3.

Conversely, when the spindle 17 rises, the drill 3 is pulled out of the printed circuit board W and the contact plate 39. In this case, since the air flows in the direction indicated by arrows C, D and E of FIG. 1, the cutting chip attached or blocked to the groove of the drill 3 is removed by the air flowing in the C, D and E directions. At the same time, the reduced temperature air contacts the drill 3 so that the drill 3 is effectively cooled.

When punching the printed circuit board 37 with the drill 3, a thin air film is formed between the lower end surface 12 of the pusher foot (that is, the lower surface of the pad 29). A portion of the high pressure air 38 ejected from the first vent 32 is shown by arrows D and E of FIG. 1 together with pressurized air blown toward the tip of the drill 3 as indicated by arrow C of FIG. It is discharged from the inlet 22 along the flow of air indicated by. Therefore, the amount of pressurized air blown toward the tip of the drill 3 is greater than that ejected from the second vent 35 to increase the cooling efficiency of the drill 3.

When the drill 3 is pulled out of the substrate W and the contact plate 39 to complete a single drilling, a thin air film is still formed between the bottom surface and the contact plate 39. Therefore, the lower surface of the pusher foot 12, that is, the lower surface of the pad 29, is separated from the contact plate 39. Thus, the drill 3 can be moved to another position for the next drilling on the printed circuit board W without raising the pad 29 (necessary for prior art). Therefore, it is necessary to give a long stroke to the spindle 17 as in the prior art. Can improve the processing efficiency.

As described above, in the present invention, the amount of pressurized air blown to the tip of the drill 3 is increased in a thin film and air is sucked in the inlet 22. Therefore, the air flow rate at the lower end opening of the pusher foot 12 is increased, so that the chip removal of the cooling effect of the drill 2 is improved.

Incidentally, the blowing of pressurized air is directed toward the center of rotation of the drill (3).

Referring to Figure 6, the processing efficiency of the present invention will be described below. Considering the cooling efficiency of the drill and the ability to remove the cutting chip, the distance G between the drill tip and the lower surface of the pad 29 needs to be 1.5 mm or more. And in order to remove the pad 29 without dragging the contact plate 39, the distance H between the bottom surface of the pad 29 and the contact plate 39 needs to be 3.0 mm or more. Therefore, the conventional punch stroke STc of the drill 3 during typical punching stacked on three printed circuit boards W is set to 10 mm. On the other hand, as the drill moves to another position in the present invention, the raising of the pad 29 is not necessary as described above. Therefore, in the present invention, the drilling stroke STi of the drill can be set within the range of 6.7 to 7.0 mm and the machining time period can be reduced from Tc to Ti every single drilling. So the present invention can increase the processing speed about 30% than the prior art.

In addition, the temperature of the air discharged from the suction port 22 is lowered as a large amount of air is supplied to the drill 3. That is, as shown in FIG. 9, when the air pressure is 6.0 Kg / cm 2 G and the nozzle diameter is about 1.5 mm, the temperature of the air discharged from the inlet port 22 is decreased from 20 ° C. to 7 ° C., where the flow rate is 200 l. / mm. Therefore, according to the above embodiment, since the air amount supplied to the drill 3 is larger than that of the conventional apparatus, the cooling efficiency of the drill 3 can be increased.

In addition, according to the present embodiment, since the amount of air supplied to the drill 3 is larger than that of the conventional apparatus in order to increase the cooling effect of the drill 3, the printed circuit board having a thickness of 1.6 mm is shown in FIG. With 9,000 drilling, the wear of the cutting edge can be improved by about 27%. In addition, even in the case of drilling having an aspect ratio of 10 to 15 over an air flow rate of 40 l / mm, the adhesion of the chip to the drill groove is small.

Claims (5)

A pusher foot for an apparatus for drilling a printed circuit board operatively supported in the axial direction of the rotor shaft, connected to a vacuum suction source, and suitable for pressing down the printed circuit board during drilling, wherein the first air passage is the pusher foot. A plurality of first vents formed on the contact surface of the pusher foot with the printed circuit board from the first supply port formed on the sidewall of the first supply port, the first supply port being connected to the pressurized air source, and the second air passage formed on the sidewall. And a second air passage extending from the supply port to the plurality of second vent openings open toward the inside of the pusher foot, wherein the second air passage communicates with the supply source of pressurized air. 2. The air passage of claim 1, wherein the first air passage extends to a first vent formed on a contact surface of the pusher foot having a printed circuit board and the second air passage extends to a plurality of second vents opened toward the inside of the pusher foot. Is formed in a pad fixed to the lower surface of the pusher foot. The pusher foot according to claim 1, wherein the second vent is directed in a tangential direction to an outer circumference of the drill supported by the rotor shaft. The pusher foot according to claim 2, wherein the second vent hole is tangential to the outer circumference of the drill supported by the rotor shaft. The pusher foot according to any one of claims 1 to 4, wherein the nozzle with the orifice is formed in the second air passage.