JPH069813U - Drill - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a drill that can perform high-precision deep hole drilling of aluminum alloys and castings at high feed rates. [Structure] The two chip discharge grooves 3 and 3 and the oil supply groove 4 provided in parallel with the groove 3 in each land portion between these grooves are cut with a helix angle of 10 to 30 ° on the drill tip side. Correct the axial rake of the blade 6 and make each groove straight from the middle to the rear end to avoid excessive groove length.
Further, the thinning groove 8 is made to largely enter the flank 9 side to widen the chip discharge space at the tip, and the central cutting edge portion is also made a positive axial rake. As a result, the sharpness is improved, the thrust force is reduced, and the discharge of chips is improved. It is more desirable to provide the guide pad portion 11 with a second cutting edge having a diameter 0.03 to 0.5 mm larger than the diameter of the cutting edge 6 and to open an oil hole in the chip discharge groove 3 on the drill tip side.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drill that can perform high-precision drilling of castings, aluminum, etc. with high efficiency.

[0002]

[Prior art]

 As a drill for high-precision machining of aluminum alloys and cast iron, for example, a pair of chip discharge grooves extending linearly in the axial direction from the tip toward the rear is provided on the outer circumference of the main body, and further, It is known that a pressing portion (pad) is provided on the outer end portion and the outer circumference of the main body at a position displaced in the circumferential direction from the outer end portion.

Further, as disclosed in Japanese Utility Model Laid-Open No. 2-94016, it is also conceivable that a small-diameter portion is continuously provided on the tip side of the drill having the above-mentioned shape and a second cutting edge is provided on the outer peripheral portion thereof. ing.

Further, as disclosed in JP-A-62-65107 and JP-A-1-117815, a pair of chip discharging grooves and a reamer groove located between the grooves are provided in parallel. Further, there is also one in which a pressing portion is provided on the outer periphery of the main body, which is located rearward of the reamer groove in the rotation direction.

[0005]

[Problems to be solved by the device]

 (1) In conventional drills used for high-precision machining of aluminum and cast iron, since the chip discharge groove is a straight groove with no helix angle, the rake angle (axial rake) of the cutting edge becomes 0 ° and the thrust force is increased. It tended to be high, and it was difficult to hope for high-efficiency machining with high feed. (2) Further, there is a problem that the chip discharging function is inferior to that of the twist drill, and troubles such as chip clogging are likely to occur when the depth of the processed hole becomes deep.

(3) Further, there is a problem that the accuracy of the machined surface is deteriorated under the high feed condition.

In view of this, the present invention aims to improve the workability of the work material, reduce the thrust force during machining, improve the chip discharge property, and improve the machining accuracy, thereby performing high-feed machining of aluminum or casting. The purpose is to enable deep hole drilling and improve life by adding oil holes.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, in the present invention, an oil supply groove parallel to the chip discharge groove is provided at each land portion between the two chip discharge grooves, and a margin portion is provided at the outer end portion of the cutting blade. Targeting the improvement of the drills, which have guide pad portions behind the oil supply groove in the direction of rotation, the chip discharge groove and oil supply groove of the drill are provided with a screw angle of 10 to 30 ° on the drill tip side, A straight groove with no helix angle is formed from the middle of the direction to the end.

[0009] More preferably, the width of the chisel edge is made 0.01 to 0.02 times the drill diameter by a thinning groove provided at the center of the tip, and the thinning groove is allowed to largely enter the flank on the other cutting edge side. As a result, a sufficient chip discharge space is secured even in the vicinity of the central cutting edge, and the thinning groove creates a positive rake angle in the central cutting edge.

Further, in order to improve the surface accuracy of the machined surface, the guide pad portion is provided with a second cutting edge having an outer diameter larger by 0.55 to 0.3 mm than the cutting edge diameter.

Further, in order to improve the life of the cutting edge portion and stabilize the deep hole machining, an oil hole is opened in the chip discharge groove.

[0012]

[Action]

 Since the chip discharge groove has a helix angle of 10 to 30 °, the cutting edge has a positive axial rake angle, which improves sharpness and reduces thrust.

Further, since the chip discharge groove having the twist angle exerts the effect of pushing up the chips, the chip discharge property is also improved. When a twist drill has a long effective blade length for deep hole machining and is used for machining aluminum alloys, etc., the chip discharge performance deteriorates due to increased outflow resistance due to the increased chip movement distance. Since the discharge groove has a helix angle only on the tip side of the drill, the advantages of the helix groove and the straight groove can be utilized in good balance. For the same reason, the penetration of cutting fluid into the cutting edge during deep hole machining is better than that of twist drills.

Further, in the case where the thinning groove is largely inserted into the flank on the other cutting edge side, the width of the chisel edge is as small as 0.01 to 0.02 times the drill diameter and the center cutting edge portion is also small. Since it has a positive rake angle, it excels in biting to the work material and thrust is further reduced. In addition, due to the expansion of the chip discharge space in the central cutting edge portion, clogging of chips at the cutting edge portion is suppressed, and the chip discharging performance is further enhanced.

Further, in the guide pad portion provided with the second cutting edge, the hole cut by the first cutting edge (the original blade of the drill) is 0.05 to 0 mm larger than the first cutting edge. The precision of the machined hole is further improved because it is finished by the second cutting edge with a large diameter of 3 mm.

In addition, the one in which an oil hole is opened in the chip discharge groove near the rake face ensures reliable oil supply to the cutting portion, improves the life of the cutting edge, and is 5 to 6 times the drill diameter. Stable cutting is possible even in deep hole machining that extends to a wide range.

[0017]

【Example】

 1 to 3 show an example of the drill of the present invention. As shown in the figure, on the outer periphery of the main body 1 having the shank 2, chip discharge grooves 3 having a substantially V-shaped cross section are provided symmetrically about the center. Further, the land portion left between the two chips discharge grooves is provided with an oil supply groove 4 through which cutting oil passes.

In the drawing, the chip discharge groove 3 is provided with a helix angle of 15 ° in the range of about 1 to 2 times the drill diameter D from the drill tip, and the groove 3 behind it is the drill shaft. It is a straight groove parallel to.

The oil supply groove 4 is parallel to the chip discharge groove 3, and therefore the groove 4 also has a helix angle of 15 ° on the drill tip side.

Reference numeral 5 denotes a margin, and the margin 5 is attached to the land portion left between the groove 4 and the groove 3 on the front side in the rotation direction. 6 is a cutting edge. The land portion left between the groove 4 and the groove 3 on the rear side in the rotation direction constitutes a guide pad portion 11 that is in contact with the inner surface of the processed hole.

A thinning groove 8 that narrows the width of the chisel edge 7 to 0.01 to 0.02D is provided at the tip of the main body. The thinning groove 8 is tilted in the twisting direction of the groove 4 and largely enters the flank 9 on the other cutting edge side. Further, the rake face 10 is partially removed so that the axial rake of the central cutting edge portion is also formed into a groove having a positive angle. In the drill shown in FIG. 3, the surface of the groove 8 is extended to the outer end of the cutting blade in order to set the axial rake over the entire length of the cutting blade 6. As a result, the actual axial rake is slightly smaller than 15 °.

FIG. 6 shows an example in which a second cutting edge and an oil hole are added to the guide pad portion of the above-mentioned drill. As shown, the guide pad portion 11 is formed with a second cutting edge 12 having an outer diameter larger by 0.05 to 0.3 mm than the cutting edge 6.

FIG. 7 is an enlarged view of the side surface of the tip portion of the drill shown in FIG. 6, and FIG. 8 is a sectional view of the same tip portion. As can be seen, the second cutting edge 12 is located rearward of the outer edge of the cutting edge 6 in the axial direction of the drill, so that the cutting edge 6 is first cut, and then the cutting edge 6 is cut. The machined hole due to is finished and cut by the second cutting edge 12.

The diameter of the second cutting edge 12 is set to be 0.1 mm larger than the diameter of the cutting edge 6 here. The clearance angle of the second cutting edge in the drill rotation direction was set in the range of -15 ° to 0 °. The clearance angle can be set to a desired value by cutting down the tip of the guide pad portion 11 as shown in FIG.

Reference numeral 13 in FIGS. 6 and 7 is an oil hole. Two oil holes 13 are provided inside the main body in parallel with the axis of the drill, and each hole opens in the chip discharge groove 3 at the twisted portion at the tip.

The diameter of the margin portion 5 is the same as the diameter of the cutting edge 6 up to a position slightly retracted from the second cutting edge 12 in the axial direction, and the portion behind the same is the same as the guide pad portion 11. It is recommended to set the diameter.

The results of the drilling test with the drill shown in FIGS. 1 to 3 will be described below. The dimensions of the drill used are diameter D = 8 mm, effective blade length L = 60 mm, core thickness 2 mm, chisel width 0.1 mm, and groove width ratio 1: 1.

Using this drill, a hole having a depth of 40 mm was machined in the work material of AC8A and FC25 under the conditions of V = 50 m / min and f = 0.1 to 0.4 mm / rev. It was proved that the thrust force was reduced compared to a conventional straight drill (same dimensions). The test results are shown in comparison in FIGS. 4 and 5. As can be seen from this figure, the thrust force of the product of the present invention is similar to that of a twist drill.

In addition, the product of the present invention has a good chip discharge performance and is capable of processing a hole depth of 6D.

FIG. 9 shows a diameter D = 10 mm, an effective blade length L = 60 mm, a core thickness of 2.5 mm, a chisel width of 0.1 mm, a groove width ratio of 1: 1, an oil hole with a tip twist angle of 15 °, and a second hole. Use a drill with a cutting edge (diameter difference between the cutting edge 6 and the second cutting edge 12 is 0.1 mm) to make a hole with a depth of 40 mm in the work material of AC8A, V = 50 m / min, f = 0.1-0.4 mm It shows the measurement results of the surface roughness of machined holes when machined by external lubrication under the condition of / rev. From this result, it is well understood that the addition of the second cutting edge is effective for improving the accuracy of the machined surface.

FIG. 10 shows the results of refueling by the external refueling method and the internal refueling method. From this, it can be seen that the drill life during deep hole drilling is improved by providing an oil hole and supplying oil internally.

[0032]

[Effect of device]

 As described above, according to the present invention, since the thrust force is reduced, high feed rate and high efficiency machining becomes possible.

In addition, the chip discharge performance is improved, and the one with a large thinning groove can easily process a deep hole having a diameter six times as large as that of an aluminum alloy or casting. Is obtained.

Further, the one provided with the second cutting edge can further improve the accuracy of the processed surface.

Further, the one having the oil hole which opens to the chip discharge groove further enhances the effect of prolonging the tool life and the depth of the machinable hole, and can be expected to improve the machining accuracy as well.

[Brief description of drawings]

FIG. 1 is a side view showing an entire embodiment of the present invention.

FIG. 2 is an enlarged front view of the drill shown in FIG.

FIG. 3 is an enlarged side view of the drill tip.

FIG. 4 is a comparison diagram of thrust forces in AC8A hole machining.

FIG. 5 is a comparison diagram of thrust forces in hole drilling of FC25.

FIG. 6 is a front view of another embodiment (a drill having a second cutting edge and an oil hole).

FIG. 7 is a side view of the tip of the above drill.

FIG. 8 is a sectional view of the above-mentioned drill.

FIG. 9 is a comparison diagram of the surface roughness of the machined hole surface with and without the second cutting edge.

FIG. 10 is a comparison diagram of hole depth and life depending on the presence or absence of an oil hole (difference in oil supply method).

[Explanation of symbols]

 1 Main Body 2 Shank 3 Chip Discharge Groove 4 Lubrication Groove 5 Margin 6 Cutting Edge 7 Chisel Edge 8 Thinning Groove 9 Flank Face 10 Rake Face 11 Guide Pad Part 12 Second Cutting Edge 13 Oil Hole

Claims (4)

[Scope of utility model registration request] 1. An oil supply groove parallel to the chip discharge groove is provided at each land portion between the two chip discharge grooves, and a margin portion is provided at an outer end portion of the cutting edge at a rear side in a rotation direction of the oil supply groove. In a drill provided with guide pad portions, the chip discharge groove and the oil supply groove have a helix angle of 10 to 30 ° on the drill tip side, and are straight grooves having no helix angle from the middle to the end in the longitudinal direction. A drill characterized by that. 2. A thinning groove for making the width of the chisel edge 0.01 to 0.02 times the drill diameter is provided at the center of the tip,
The drill according to claim 1, wherein the thinning groove largely enters the flank on the other cutting edge side, and further, a positive rake angle is generated in the central cutting edge portion. 3. The drill according to claim 1, wherein the guide pad portion is provided with a second cutting edge having an outer diameter larger by 0.05 to 0.3 mm than the cutting edge diameter of the drill. 4. The drill according to claim 1, 2 or 3, wherein an oil hole is opened in the chip discharge groove in front of the drill.