JPS63260713A - Blank for extra-hard solid drill and its manufacture - Google Patents

Abstract

PURPOSE:To shorten the grinding operation and uniformize shape precision and strength of the cutting edge by finish-grinding after forming the outer periphery of the fail shank, and tip of the cutting edge, with lands in the vicinity and margin part and leaving grindings discharge-groove finishing allowance. CONSTITUTION:The outside dia. d1 of the tail shank 1, tip of cutting edge 2, and its neighborhood 3 are formed greater by an amount corresponding to the finish margin x with respect to the dimension d at the completed time of the product, and the radius d2 of the intermediate part 4 is formed smaller than the specified dimension. The dimension of the intermediate part 4 is made small for the purpose of absorbing such deformation as warp, etc., generated in sintering process, and the length l of the neighborhood 3 is set according to the amount used in re-grinding, that shall be approx. 1-3 times as large as the drill dia. The core thickness y1 of the neighborhood 3 shall be greater than the core thickness dia. y2 of the intermediate part 4, and the lands of the tail shank 1, tip of cutting edge 2, and its vicinity, margins and grinding discharge groove are finished by grinding to provide a completed drill product.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a solid carbide drill blank and a method for manufacturing a solid carbide drill using the blank.

(Conventional technology and its problems) Cemented carbide shrinks in size and undergoes deformation such as warping before and after the sintering process.For this reason, when a solid drill is formed from cemented carbide, the entire circumference must be Grinding is performed using a diamond grindstone, etc. to remove excess deformation and finish the desired shape and dimensions. However, the grindability of cemented carbide is significantly worse than that of -11 steel, so the grinding process is difficult. There is a problem in that it takes a long time to process, and the grinding wheel is heavily worn out, resulting in high manufacturing costs.

Conventionally, in order to deal with the above-mentioned problems, solid carbide drills have been proposed in which part of the drill surface is a non-ground surface. As shown in Fig. 3, this drill has the tip cutting edge part 10, the outer peripheral margin part 11, and the rear end shank part 12, which are shaded in the figure, formed by grinding and machining, and the other parts are pre-sized to the required dimensions. It is formed smaller and left as a non-grinding surface, and has the advantage of reducing the grinding time and lowering manufacturing costs because there is less grinding surface compared to a drill that grinds the entire surface.

However, in this type of drill, the drill body undergoes deformation such as warping before and after the sintering process as described above, so the shape of the finished outer peripheral margin part 11 is uneven in each part of the drill. It's easy to become a thing. When machining is performed with such a drill, the guiding performance of the drill itself may become unstable, resulting in large cutting vibrations. Furthermore, since the chip discharge groove 13 is unmachined, there is a problem in that when re-grinding is performed, the shape of the tip cutting edge changes each time, resulting in variations in cutting performance and cutting edge strength.

[Purpose of the Invention] In view of the above problems, the present invention has been developed by further improving the solid carbide drill shown in Fig. 3 to shorten the grinding work and improve the shape accuracy and strength of the cutting edge portion. The object of the present invention is to provide a blank for a solid carbide drill that enables the production of solid carbide drills, and a method for manufacturing a solid carbide drill using the blank.

[Means to achieve the purpose]

As shown in FIGS. 1(a) and 1(b), a solid carbide drill blank, which is one of the objects of the present invention, has a rear end shank portion 1, a tip cutting edge portion 2, and a portion 3 in the vicinity thereof. It is formed to a size that leaves a finishing allowance for machining with respect to the required dimensions, and other parts are formed smaller than the required dimensions.

That is, the above-mentioned blank has been machined (mainly by grinding) so that the outer diameter (dl) of the rear end shank portion 1, the tip cutting edge portion 2, and its neighboring portion 3 is adjusted to the specified dimension (d) at the time of product completion. It is formed larger by the finishing amount (X) (c!, >
d) Also, the diameter dimension (d2) of the intermediate portion 4 between the vicinity portion 3 and the shank portion 1 is smaller than the specified dimension (d>L).

The reason why the diameter of the intermediate portion 4 is made small in this way is to absorb deformation such as warpage that occurs during the sintering process. The length 2) of the vicinity portion 3 is set in consideration of the amount to be used by re-grinding, and is normally 1 to 3 times the drill diameter (d).

In addition, regarding the core thickness dimension, the core thickness diameter (yl) of the neighboring portion 3 is made larger than the core thickness diameter (y2) of the intermediate portion 4 ()'+>y
z) As will be described later, when machining the chip discharge groove over the entire length of the drill, the core thickness of the entire drill is formed to be larger than the required core thickness diameter.

Next, the method for manufacturing a solid carbide drill using the above-mentioned blank, which is the second object of the present invention, is as shown in FIG. , the tip cutting edge 2, the land portion (3a) and margin portion (3b) of the tip cutting edge vicinity portion 3, and at least the portion near the tip cutting edge of the chip evacuation groove 5 are finished by machining to form a completed drill. It is something to do.

In the drill manufactured by the above method, the entire surface of the tip cutting edge part 2 and its vicinity 3 is machined, so the cutting edge part 2 and margin part (3b) actually used for machining are always uniform. You can get something with a different shape. In addition, since the chip evacuation grooves 5 up to the vicinity part 3 are formed in a manner that is accurately distributed with respect to the drill axis through machining, the shape of the tip cutting edge after re-grinding can be maintained in a constant shape. can be formed into

Furthermore, since cutting of the intermediate portion 4 is omitted, the grinding work can be shortened compared to the case where the entire surface of the drill is ground. The grinding time is approximately 25 minutes in the case of full-surface machining of a drill, whereas it is approximately 20 minutes in the case of the present invention, making it possible to achieve a significant time reduction of 20%.

Further, the chip discharge groove 5 may be finished over the entire length of the drill by machining. In this way, in each part of the drill, the chip discharge groove 5 can be formed in an accurately symmetrical position with respect to the drill axis (because the cross-sectional shape is uniform in each part of the drill), so that the cutting force is not affected. This makes it possible to provide a drill with good cutting balance, which is less susceptible to unbalanced deformation when cutting.

In addition to the above-mentioned solid carbide drill, the method for producing a blank skin of the present invention can also be applied to a drill whose main component is TiC or TiN.

〔Effect of the invention〕

As described above, according to the present invention, the rear end shank part, the tip cutting edge part, and the vicinity thereof are finished by machining, so the shape and dimensions of the parts that require precision and the parts used for cutting. can always obtain uniform
It is possible to provide a drill with stable cutting performance down to 0 m. Further, since machining of parts other than those mentioned above can be omitted, the time required for machining can be shortened, and manufacturing costs can be reduced.

[Brief explanation of the drawing]

FIG. 1(a) is a partially longitudinal side view showing a solid carbide drill blank according to the present invention, FIG. 1(b) is a plan view of the same,
Fig. 2 (a) is a partially longitudinal side view showing a solid carbide drill formed by the manufacturing method of the present invention, (b) is a plan view of the same, and Fig. 3 is a side view showing a conventional solid carbide drill. It is.

Claims (2)

[Claims] (1) The rear end shank part, the tip cutting edge part and its vicinity are formed to a size that leaves a machining finishing allowance for the required dimensions, and the parts other than the above are formed smaller than the above required dimensions. A solid carbide drill blank characterized by: (2) The rear end shank portion, the tip cutting edge portion, and its vicinity are formed to a size that leaves a finishing allowance for the required dimensions, and the portions other than the above are formed to be smaller than the required dimensions. A solid carbide drill blank is manufactured, and the outer periphery of the rear end shank, the tip cutting edge, the land portion and margin near the tip cutting edge, and at least the tip cutting edge of the chip evacuation groove are manufactured. A method for producing a solid carbide drill, characterized by finishing the adjacent portion by machining to form a completed drill.