JPH11226810A - Twist drill, material for twist drill having oil hole, extrusion molding device for the material and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twist drill excellent in cutting property and discharging property for chip. SOLUTION: In this type of twist drill, a lead of a chip discharging groove (a) is varied in a length position. In a material for the twist drill having oil holes (b), a lead of the spiral small hole is varied in its longitudinal direction. On the outer periphery of the material, a mark indicating a direction of the spiral hole or the lead is written. This marking which is formed on the outer periphery for indicating the direction or the lead of the spiral holes is adapted to an extrusion molding method and device for the twist drill material having the oil holes (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twist drill, and more particularly, to a twist drill having an oil hole having a helical small hole continuous around an axis which is a cutting oil supply hole, a material for the twist drill having an oil hole, and a twist drill. The present invention relates to an extrusion molding apparatus and an extrusion molding method.

[0002]

2. Description of the Related Art The twist angle of a chip discharge groove of a twist drill determines the squeeze angle in cutting at the tip of the drill and is related to the chip discharge operation. Further, in a conventional twist drill with an oil hole, a pair of small holes are provided spirally in a substantially constant lead around an axis.
The material for twist drills with oil holes manufactured from ingot material is
After drilling two holes in the short rod-shaped material symmetrically on both sides of the axis and parallel to the axis with a drill, the material is drawn to the desired cross-sectional shape and dimensions. It is manufactured by mechanically twisting the hole so that the hole has a predetermined size and a constant lead. The drill is manufactured by forming a chip discharge groove in the outer diameter of this material by grinding or cutting. In the case of the powder metallurgy method, a powder kneaded body such as a high-speed tool steel is extruded into a green having a pair of straight holes by an extrusion molding method, which is then sintered, and then subjected to mechanical processing in the same manner as the above-described ingot material. A method of forming a helical small hole with a constant lead by imparting a twist is used.

[0003] Furthermore, in the powder metallurgy method, it has been proposed to form a green state having spiral small holes. That is, Japanese Patent Application Laid-Open No. 61-22710
No. 1 and Japanese Patent Application Laid-Open No. 1-156405 disclose a forming method in which a kneaded body is extruded and simultaneously subjected to a motion torsion to obtain a material for a drill having a spiral small hole.

[0004] The present applicant also discloses a method of torsionally extruding a sintering material in which a torsion hole can be obtained as it is, and a method of rotating a mandrel having a helical torsion pin to impart a torsional motion to a material to be extruded. Without forcing, the extrusion method and the device in which a twist hole is obtained,
When introducing the plastic kneaded material from the side to the duct portion where the mandrel having a rotatable spiral torsion pin is disposed at the rear end, the ratio of the distance from the introduction portion to the extrusion die to the diameter of the duct, that is, Extrusion methods have been developed that can prevent the displacement of the small hole position by optimizing the slenderness ratio, and are disclosed in JP-A-1-96305 and JP-A-3-10, respectively.
7401 and JP-A-8-225809.

[0005]

It is desirable that the tip of the chip discharge groove of the twist drill is determined in terms of the cutting property on the front end side and the chip discharge property on the rear end side. There are different leads on the side and the rear end. When such a drill is applied to a twist drill with an oil hole, since the oil hole is not allowed to open in the chip discharge groove, the lead of the spiral small hole is also lead to the chip discharge groove. It is necessary to change according to.

However, the conventional twist drill is
Regardless of the drill with oil hole or the drill without oil hole, the lead of the chip discharge groove is a compromise between both the cutting performance and the chip discharge performance and is constant, so it is sufficient under severe drilling conditions etc. Performance could not be demonstrated. Further, as described above, the lead of the spiral small hole of the twist drill with an oil hole manufactured from the ingot is constant. Also, among the methods of extruding while giving a torsional motion to an extruded product, for example, Japanese Patent Application Laid-Open Nos. 61-227101 and 1-156
No. 405 and Japanese Patent Application Laid-Open No. 1-96305, these methods use a torsion groove provided in the inner diameter of a die to impart a torsional motion to a material to be extruded. Even in these methods, the obtained spiral stomatal leads are almost constant.

Further, the methods disclosed in JP-A-3-107401 and JP-A-8-225809 do not forcibly rotate a material to be extruded, but instead rotate a mandrel to form a spiral small hole. In this method, the leads of the helical pores obtained are almost constant. Therefore, with the conventional material for a twist drill with an oil hole, it was not possible to manufacture a drill in which the lead of the chip discharge groove changed depending on the position in the longitudinal direction. Since twist drills with oil holes are generally used in situations where the drilling conditions are severe, it is desirable that the lead of the chip discharge groove be optimized at each part if possible.

In view of the above, the present invention provides a twist drill, a material for a twist drill having an oil hole, an extrusion molding apparatus and an extrusion molding method for the material, which can improve the cutting efficiency and enhance the chip discharge efficiency. The purpose is to provide.

[0009]

Means for Solving the Problems The present inventor has determined the twist angle of the chip discharge groove of the twist drill, the cutting ability on the tip side,
At the rear end side, attention was paid to the fact that the drilling efficiency can be improved by determining each in consideration of the state of chip discharge. Further, the present inventor provides a rotatable mandrel with an oil hole forming pin rotatably in the extrusion opening of the die, and changes the rotation speed of the mandrel according to the extrusion speed during extrusion, thereby forming a spiral. It has been found that the reticulated streaks can be varied over the length of the extrusion. The present inventor further marks the oil hole lead or the mark indicating the direction of the oil hole with respect to the axis on the outer peripheral surface of the extruded body so that the oil hole is formed at the time of forming the chip discharge groove. It was noted that opening to the discharge groove can be avoided.

That is, the first invention of the present application is a twist drill characterized in that the lead of the chip discharge groove changes in the longitudinal direction, and this drill has a spiral shape around the axis. It is desirable to have an oil hole connected to the hole.
Further, according to the second invention of the present application, the lead of the oil hole spirally connected around the axis changes substantially stepwise in the longitudinal direction, or the ratio between the maximum and minimum leads is 1. A third aspect of the present invention is a material for a twist drill with an oil hole, which is at least one of at least one of the following: a mark indicating a direction or a lead of the oil hole with respect to the axis on an outer peripheral surface. It is a material for a twist drill with an oil hole, which is characterized in that the drill is provided.

According to a fourth aspect of the present invention, there is provided an extrusion die provided at a tip of an extrusion molding apparatus, and a mandrel having a screw hole forming pin provided in a spiral opening at an extrusion opening of the extrusion die. A twisting device with an oil hole, characterized by comprising a marking device for marking on the outer peripheral surface of the material to be formed in accordance with the rotation angle of the mandrel or the lead of the helically continuous hole to be formed. This is a device for molding materials.

The fifth invention of the present application is directed to a kneaded product in which an organic binder is added to a single alloy powder or a mixed powder obtained by mixing a plurality of types of powders having a composition corresponding to the composition of the final product, and The kneading is performed through a synthetic opening formed by an extrusion die provided at a tip of an extrusion molding device and an oil hole forming pin spirally connected to an extrusion opening of the extrusion die attached to a mandrel. The body is extruded to form a molded body having a helically continuous hole around the axis, and a mark corresponding to the rotation angle of the mandrel or the lead of the helically continuous hole to be formed is formed. A method for extruding a material for a twist drill with an oil hole, characterized in that the material is applied to an outer peripheral surface of a twist drill.

In the twist drill of the present invention, the torsion angle of the chip discharge groove at the tip is determined with emphasis on the cutting at the tip, and the rear is determined with emphasis on chip discharge. Since the two portions have different angles, each portion works effectively, and the drilling efficiency and life can be increased.
It is desirable that the drill of the present invention has an oil hole spirally connected to the periphery of the axis and from which the lubricant is supplied.

The first material for a twist drill having an oil hole according to the present invention.
Since the lead of the oil hole changes in the longitudinal direction, the chip discharge groove is processed in accordance with the lead, thereby preventing the oil hole from being opened in the groove while preventing the oil hole from opening in the groove. It is possible to manufacture a twist drill in which the lead changes in the longitudinal direction of the drill. Therefore, according to the material, the twist drill of claim 2 can be obtained in a wide lead change range.

Conventionally, in order to prevent the oil hole from being opened in the groove when the chip discharge groove is formed by cutting or grinding, conventionally, efforts have been made to reduce variations in the lead of the material for the twist drill with oil hole. Ingenuity has been devised. However, despite these various efforts and ingenuity, it is quite difficult to keep the variation of the oil hole lead within ± 1%, usually within ± 3% and continuously in the longitudinal direction. Was scattered. For this reason, when the drill material is long, the processing of the chip discharge groove is performed for each relatively short length, and cut each time, and proceeds while confirming the direction of the oil hole at the end face. This has been a factor that hindered the efficiency of grooving.

The first aspect of the twist drill material with an oil hole according to the present invention is that the lead of the oil hole does not change continuously, but rather in a stepwise manner. The lead is different from another constant length section in the same material) or the ratio of the maximum to the minimum lead is 1.1
This is at least one of the above, and the conventional one is not included. The reason why the maximum and minimum lead ratios are set to 1.1 or more is to surely avoid the overlap with the conventional variation range of the leads, and to reduce the lead ratio in the apparatus invention and method invention of the present application. Is 1.1 or more can be manufactured sufficiently. Therefore, this ratio is 1.
It may be two or more, or even 1.3 or more. If the lead is stepwise, it is convenient because an optimum tool shape and the like can be selected for forming a chip discharge groove of the lead.

In a second aspect of the present invention, a mark is provided on the outer peripheral surface to indicate the direction of the oil hole in the direction of the axis of the oil hole or the lead of the hole extending in a spiral. Therefore, not only a material manufactured by suppressing the fluctuation of the lead of the oil hole, but also a material having a long length even if the lead of the oil hole changes according to the longitudinal position according to the present invention. However, if the processing for forming the chip discharge groove is performed using this mark as an index, the oil hole will not be opened in the groove. As described in the embodiments, it is most preferable that a small dent is formed at a typical position other than a margin portion such as the center in the width direction of a chip discharge groove to be formed at the time of extrusion molding. Easy and simple. However, the mark is not limited to this, and after refinishing after the outer diameter finish grinding after sintering, it is re-attached based on the mark before grinding or X after grinding.
The oil holes may be detected by a line or the like, or the result may be applied by a paint or the like, a numeral, or another symbol.

According to the present invention, there is provided an extrusion molding apparatus and method for forming a small hole which is an oil hole on an outer peripheral surface of a material to be extruded. Since the mark indicating the lead, such as a representative point in the longitudinal direction such as a start point, an end point, or a center point, or a point at which the rate of change of the lead is changed, is automatically added, the extruded material is fired. For sintering, even when shrinking during sintering or arbitrarily changing the lead of the small hole that becomes an oil hole, the small hole does not open into the groove when forming the chip discharge groove. Material can be produced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a twist drill of the present invention having an oil hole b. The drill is smaller than the rear end side of the point A so that the rake angle in cutting at the time of drilling of the lead of the chip discharge groove a at the front end side from the point A becomes an appropriate value. Are also made smaller according to the groove a so as not to open into the groove. On the other hand, on the rear end side from the point A, the chip discharge groove a (therefore, oil hole b
) Is processed to be larger than the tip side in view of the dischargeability of chips.

Next, the second to fifth inventions of the present application will be described in detail based on an example of an extrusion molding apparatus used for carrying out the invention. FIG. 2 is a sectional view of one embodiment of the extrusion device of the present invention. A die 2 is fixed to an outlet of a base 1 which communicates with an outlet of an extruder (not shown) and forms a duct space having a circular cross section having two bent sides as axes. A mandrel 6 for extending a helical pin 7 at the extrusion opening of the die is provided along the axis of the duct space on the extrusion opening side. Control device 4
Is controlled by inputting the extrusion speed from a speed sensor 3 provided at the exit of the die 2 and controlling the motor 5 so as to attain a rotation speed corresponding to a preset stationary or changing lead according to the extrusion speed. The angle of the pin portion 7 with respect to the axis is detected by the angle sensor 9, and the output of the mark sensor 10 is added to the output of the speed sensor 3 in consideration of the axial distance X from the extrusion opening. Under control, the direction of the spiral hole or the lead of the spirally continuous hole is displayed on the outer peripheral surface of the extruded material by numerical values, symbols, or the like.

The die 2 used had an extrusion opening having a diameter of 21 mm, and the length of the fixed portion was relatively short.
The spirally connected pin 7 attached to the tip of the mandrel 6 has a diameter of 2.7 mm and a center-to-center distance of 8.96 m.
m, the spiral lead is 88.1 mm. Further, the control device 4 changes the lead from 75.4 mm to 105.4 mm in the total length of 176.7 mm according to the extrusion speed from the speed sensor 3.
Up to 1.8 mm and from 101.8 mm to 75.4 m
m (101.8 / 75.4 ≒ 1.35), the rotation speed of the motor 5 is set so as to repeat a pattern in which the lead is continuously changed. It is set so that the marking device 10 is operated at the point where one of the perpendicular bisectors of the line connecting the small holes on the cross section perpendicular to the axis intersects with the outer peripheral surface to perform marking (dot stamping in this embodiment). I have.

The extruder of the above-described apparatus was driven, and after sintering, a powder having a composition corresponding to AISI T15 was mixed and kneaded with a binder, extruded from the extrusion die 2, and the motor 5 was driven to perform extrusion molding. The extruded product is extruded to a predetermined length and cut, and has an outer diameter of 21.1 mmφ and a hole diameter of 2.71 m.
A material for sintering having mφ, a distance between holes of 8.93 mm, and a mark on the outer peripheral surface of the formed body was obtained.

This sintering material is placed in a reducing atmosphere at 500
After holding at ~ 700 ° C for 3 hours to remove the binder,
Vacuum sintering was performed at 1200 to 1250 ° C. for 3 hours. After sintering, the result of dimensional measurement was as follows:
(Target 17.1mmφ), hole diameter 2.21mmφ (target 2.2mmφ ± 0.1mm), distance between holes 7.27mm
(Target 7.3 ± 0.4 mm). Examination of the extrusion molding apparatus and the sintered product after the test showed that no adverse effect was caused by rotating the pin 7 having a predetermined lead differently from that of the lead.

In this embodiment, in order to prevent breakage due to sudden rotation change of the helical pin during molding, the lead repeatedly changes from a short side to a long side and from a long side to a short side. After examining the length of the helical pin 7 and the length of the fixed portion of the extrusion opening of the die, the lead is changed from short to long, then rapidly shortened and again changed from short to long. It turns out that it is also possible. Alternatively, the reverse pattern may be used. Also,
Here, an example in which high speed tool steel powder equivalent to AISI T15 is used as the material to be extruded has been described. However, the present invention is not limited to this and can be applied to various materials such as other tool steels, cemented carbides, and ceramics. .

With the tip end obtained above as the short lead side, a drill (outer diameter: 17.0 mm, tip lead: 61.5 m) having a chip discharge groove almost matched with the lead
m, lead at point 140mm from the tip: about 83mm)
And the lead of the spiral small hole and the chip discharge groove is 71.8 mm.
When a cutting comparison test was conducted with a constant drill and a drilling hole depth of 140 mm, the cutting speed could be increased about 1.12 times as compared with a drill having a constant spiral small hole lead.

[0026]

As described above, the twist drill according to the first invention of the present application can improve the cutting performance and the efficiency of chip discharge, and therefore can increase the cutting speed and reduce the processing cost. Further, the twist drill material of the second invention is an intermediate product essential for manufacturing the twist drill of the first invention having an oil hole. Further, in the material of the third invention, there is a mark provided on the outer peripheral surface of the material even if the lead of the spiral small hole changes in the longitudinal direction or the material is long for improving the processing efficiency. Therefore, if the chip discharge groove is machined according to the mark, the oil hole does not open to the chip discharge groove, and the processing of the chip discharge groove can be made more efficient, and the performance is relatively low cost and high performance Can be obtained. Further, according to the devices and methods of the fourth and fifth inventions of the present application, the marking is automatically applied to the device of the third invention, which is indispensable for the production of this product.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a twist drill according to the present invention in which a lead of a chip discharge groove changes in a longitudinal direction.

FIG. 2 is a sectional view showing an example of the extrusion molding apparatus of the present invention.

[Explanation of symbols]

a Chip discharge groove, b Oil hole, X-axis distance, 1 cap, 2 dice, 3 speed sensor, 4 control device, 5 motor, 6 mandrel, 7 pin, 8 detected part, 9
Detection sensor, 10 marking device

Claims (6)

[Claims] 1. A twist drill, wherein a lead of a chip discharge groove changes in a longitudinal direction. 2. The twist drill according to claim 1, further comprising an oil hole spirally connected around the axis. 3. An oil hole reed that spirals around an axis.
Characterized in that the material is substantially stepwise changed in the longitudinal direction and / or the ratio of the maximum to minimum leads is at least 1.1. . 4. A material for a twist drill with an oil hole having an oil hole helically connected around an axis, a mark indicating a direction or a lead of the oil hole with respect to the axis on an outer peripheral surface thereof. A material for a twist drill with an oil hole, characterized in that the material is provided with an oil hole. 5. A mandrel having an extrusion die provided at the tip of an extrusion molding device, an oil hole forming pin spirally connected to an extrusion opening of the extrusion die, and a rotation angle of the mandrel. Alternatively, there is provided an extruding apparatus for a raw material for a twist drill with an oil hole, comprising a marking apparatus for performing marking in accordance with the lead of a spirally formed hole on an outer peripheral surface of a material to be formed. 6. An organic binder is added to an alloy powder having a composition corresponding to the composition of the final product or a mixed powder obtained by mixing a plurality of powders to form a kneaded body, and the kneaded body is provided at the tip of an extrusion molding apparatus. The kneaded body is extruded around an axis by extruding the kneaded body through a synthetic opening formed by the extruded die provided and an oil hole forming pin attached to the mandrel and spirally connected to the extruded opening of the extruded die. A molded body having a helically continuous hole is formed at the same time, and a rotation angle of the mandrel or a reel of the helically continuous hole to be formed is formed.
A method for extruding a material for a twist drill with an oil hole, characterized in that a marking in accordance with the material is applied to the outer peripheral surface of the material to be extruded.