JPH0471642B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a solid carbide drill with an oil hole used for drilling.

[Conventional technology]

A drill generally consists of a body with a spiral blade and a shank, but it is necessary to inject cutting oil to prevent the temperature of the cutting blade from rising during drilling operations and to facilitate the evacuation of chips. .

For this reason, drills with multiple oil holes are commercially available, but these drills are made of steel. This steel drill is obtained by hot twisting the body after forming multiple straight holes. Such a method is possible with ductile materials such as steel, but not with brittle materials such as cemented carbide. Therefore, in the case of conventional carbide drills, cutting oil was injected from the entrance of the hole formed by the drill, which not only did not allow sufficient cooling of the cutting edge but also insufficient discharge of chips.

Recently, a paste-like cemented carbide raw material to which a sticky semi-fluid or fluid temporary binder has been added is extruded through an extrusion die with a helical guide pin, and the extruded part is given an appropriate twist. A drill with a pointed tip has also been proposed in which a carbide cutting edge is formed by adding the carbide, and the cutting edge is joined to the twist drill body. (Unexamined Japanese Patent Publication No. 54-159791) [Problems to be Solved by the Invention] However, in this method, the accuracy of the oil hole formed by the guide pin is not necessarily sufficient, and the oil hole in the twist drill body is It is extremely difficult to accurately position and join the oil hole of the carbide blade and the oil hole of the carbide blade. Also, since the carbide cutting edge is joined, the strength of the drill is not necessarily satisfactory.

Moreover, the extrusion process must be carried out by accurately controlling the extrusion speed and twisting speed, which is difficult in practice and has poor productivity. Even if an attempt was made to form a solid carbide drill using the method disclosed in JP-A No. 54-159791, the guide pin could not be removed from the molded product, so the method of forming only the body and joining it to the shank had to be resorted to. , unsatisfactory in terms of strength and productivity.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a solid drill with an oil hole made of cemented carbide, which solves the above-mentioned problems and which has been difficult with the prior art.

[Means for solving problems]

As a result of intensive research, the inventor of the present invention formed a straight oil hole and a groove for forming a flute part in advance, made the cemented carbide into a complete sintered body, and then heated the material to create a helix angle. The present invention was completed based on the discovery that a solid drill having a spiral oil hole can be formed by pressurizing and deforming it with a die having a spiral hole.

That is, the manufacturing method of the solid carbide drill with an oil hole of the present invention includes: A process of forming a round bar having a plurality of straight thin holes using an extrusion method A process of deplasticizing the material A flute is formed by machining A process to form straight grooves for sintering of cemented carbide A process in which the material is deformed under pressure using a die with a helix angle under hot conditions (1100 to 1300℃) to give it a twist. It is characterized by this.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case of manufacturing a two-blade drill as an embodiment of the present invention will be described with reference to the drawings.

Process As shown in FIG. 1, a round bar 2 made of a cemented carbide material and having two straight oil holes 1 is manufactured. When manufacturing this round bar, the most preferable method is extrusion molding, in which a plasticizer is added to cemented carbide powder to form a paste, but the method is not limited to extrusion molding. The body may be temporarily sintered and then holes may be formed.

Process Next, this extruded body is pre-sintered at approximately 800°C.
Preliminary sintering removes the plasticizer added for extrusion and provides the strength necessary for machining in the process.

Process Next, as shown in FIG. 2, a straight groove 3 is machined using a grindstone. The reason why the grooves 3 are formed is that since the amount of deformation of cemented carbide during hot working is small, hot working is performed after forming the cross-sectional shape of the cemented carbide into a shape that approximates the cross-sectional shape of a drill.

process Perform main sintering to obtain a complete sintered body.

Cemented carbide shrinks to about 80% of the size of the extruded product during sintering (the relative density of the extruded product is around 50%, and the relative density becomes almost 100% after main sintering). Otherwise, hot twisting cannot be performed.

In addition, since the main sintering process yields a shape that is almost similar to that of the compact, the dimensional accuracy can be maintained by machining the grooves 3 in the process to approximate the shape of the final product. Accuracy can also be increased.

Process Next, as shown in Fig. 3, the round bar 2 is placed in the guide cavity 7 of the mold 5, and the temperature
Pressure is applied from the top as shown by arrow A within a temperature range of 1300°C. Pressure may be applied by simply applying pressure to the upper end of the round bar 2, but when rotating the round bar 2 during molding, hold the upper end of the round bar 2 with a suitable jig.
Rotate the jig while pressing it downward. As shown in FIG. 4, the structure of the cavity 8 of the die 6 has the cross-sectional shape of a desired drill body and is spiral at a desired helix angle, so that the sintered body 2 is deformed into the shape of the desired drill body. go. Figure 5 shows the appearance after deformation. Since the round bar 2 is uniformly deformed without being displaced during hot working, the oil hole 1 extends neatly in a spiral shape within the body 10, as shown in FIG. Since the oil hole usually has to be located within the land, it is very advantageous that the oil hole does not shift in position. This is because the amount of deformation of the cemented carbide is small, and the groove 3 is provided to approximate the cross-sectional shape of a drill.

Further, the high temperature plastic deformation device used in the present invention is shown in FIG. 3, where 4 represents a heater, 5 represents a mold, and 6 represents a die.

As the heater 4, any heater can be used as long as it can raise the temperature to a temperature (1100 to 1300°C) at which the cemented carbide is easily plastically deformed, and high frequency heating is particularly preferred.

The mold 5 has a cavity 7 in the center for guiding a round bar. The mold 5 may have a two-part structure to facilitate taking out the molded round bar 2, but it may be an integral piece if the molded product is taken out while rotating. The mold 5 is preferably made of carbon from the viewpoint of heat resistance.

The die 6 has a cavity 8 having a cross-sectional shape and helix angle corresponding to the molded product, and is made of ceramic with high heat resistance and high temperature strength in order to mold the cemented carbide under hot pressure. is preferable. Furthermore, carbon can also be used in terms of lubricity and heat resistance. Dice 6 is
A base 9 with a hole of the same size as the guide 7 in the center
It is attached to the recessed part of the top surface. Like the mold 5, the base 9 is also preferably made of carbon.

Although the present invention has been described above using examples, the present invention is not limited to the above-mentioned examples.
It goes without saying that various cross-sectional shapes, for example three or more blades, are also possible.

In addition, the term "oil hole" used in this specification
is a hole that passes through the drill and can be used for any type of cutting fluid.

〔Effect of the invention〕

According to the present invention, it is possible to manufacture a solid cemented carbide drill in which a plurality of oil holes are accurately arranged in a spiral manner along a spiral cutting edge. In this way, the completed solid drill can be made into a product by simple finishing processing.

When used for drilling, the oil hole extends to the tip of the cutting edge, allowing for sufficient cooling of the cutting edge and smooth removal of chips, making it possible to provide a high-performance solid drill.

[Brief explanation of drawings]

Fig. 1a is a plan view of a round bar made of cemented carbide material with oil holes, Fig. 1b is a left side view of the round bar of Fig. 1a, and Fig. 2a is a diagram of a round bar with grooves formed therein. FIG. 2b is a plan view, and FIG. 2b is a left side view of the round bar in FIG. 2a. FIG. 3 is a schematic cross-sectional view of the drill forming device, and FIG. 4 is a line segment X--
5 is a cross-sectional view taken along X', and FIG. 5 is a front view of a solid drill obtained by the apparatus of FIG. 3. 1...Oil hole, 2...Round bar, 3...Groove, 4...Heater, 5...Mold, 6...Dice, 8...Cavity, 9...Base.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a solid carbide drill with an oil hole, characterized in that the solid carbide drill with an oil hole is manufactured by the following process. Process of forming a round bar with multiple thin straight holes using extrusion process Process of deplasticizing material Process of forming straight grooves to form the flute of a drill by machining Process of forming straight grooves to form the flute of a drill A process in which the material is deformed under pressure using a die with a helix angle at a temperature of 1100 to 1300℃ to give it a twist.