JP2013049098A - Drill grinding device, its parts and drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill grinding device which processes a drill so that a larger number of cutting processes than a conventional device can be continuously performed.SOLUTION: This drill grinding device grinds the drill formed with a drill cutting edge including a rake face and a chisel cutting edge which is continuous to the drill cutting edge by making the drill abut on the grinding face of a rotating grinding stone 1. The grinding face has a drill cutting edge grinding face 11 for grinding the drill cutting edge and a flank 12 which is formed continuing to the drill cutting edge grinding face 11. An inclination angle formed of the drill cutting edge grinding face 11 and the flank 12 is within a range of 20° to 26°, and the length of the flank is not shorter than 1.1 [mm]. By an effect that the drill cutting edge abuts on the rotating drill cutting edge grinding face 11, and the rake face of the drill and the chisel cutting edge abut on the flank 12, an angle formed of the drill cutting edge and the chisel cutting edge is formed within a range of 154° to 160°.

Description

  TECHNICAL FIELD The present invention relates to a drill tip processing apparatus for performing cutting processing such as drilling on a structure spot-welded by overlapping sheet metal, and particularly used for cutting high-hardness steel plates used in automobiles and the like. The present invention relates to an apparatus suitable for polishing processing of a tip of a drill, its components, and a drill.

  Conventionally, when disassembling an automobile body or the like, a metal plate is separated by peeling a portion (hereinafter referred to as “spot welded portion”) spot-welded by overlapping metal plates together by cutting. Has been done. It is common to use a drill for cutting. The cutting edge of the drill is worn by continued use, and finally becomes in a state where cutting cannot be performed. Therefore, it is necessary to re-polish the worn drill tip. Patent Document 1 discloses a conventional drill polishing apparatus for polishing a tip of a drill.

WO99 / 28082

  The drill polishing apparatus of Patent Document 1 is an apparatus for polishing a candle type drill that can be used for peeling off spot welds used in a vehicle body or the like. In this drill polishing apparatus, a drill is fixed to a drill grinding table, and the cutting edge of the drill can be polished by a parallel surface that is a polishing surface of the grindstone. Moreover, a drill can be fixed to a drill thinning stand, and a thinning process can be performed by the inclined surface of a grindstone, and a 2nd parallel surface.

  It is desirable that the drill can be processed into a drill with higher work efficiency than before by using a drill polishing apparatus. In particular, a high-tensile steel plate having a high tension is used for a metal plate constituting a body of an automobile in recent years in order to reduce the thickness. In contrast to high-strength steel plates, conventional drills are severely worn by the cutting blades, and it is difficult to continuously perform machining on a large number of spot welds.

  The inventors of the present application have found that, by devising the shape of the chisel at the tip of the drill, it is possible to efficiently cut a spot weld with high hardness like a high-tensile steel plate. Specifically, the efficiency of cutting is improved by forming the angle of the chisel cutting edge with respect to the cutting edge and the width of the base end of the chisel within a predetermined range. In the drill polishing apparatus of Patent Document 1, the inclination angle of the flank with respect to the parallel surface (drill cutting blade polishing surface) is 35 degrees, and the angle of the chisel cutting blade with respect to the cutting blade can be formed within the predetermined range. Have difficulty.

  In view of such problems, an object of the present invention is to provide a drill polishing apparatus, a part thereof, and a drill for performing drill processing so that a larger number of cutting operations can be continuously performed than in the past.

The drill polishing apparatus of the present invention that solves the above-described problems makes a drill in which a drill cutting edge including a rake face and a chisel cutting edge connected to the drill cutting edge are brought into contact with the polishing surface of a rotating grindstone. This is a drill polishing apparatus that performs polishing by using the above method. The polishing surface has a drill cutting edge polishing surface for polishing the drill cutting edge, and a flank formed in communication with the drill cutting edge polishing surface. The inclination angle formed by the drill cutting edge polished surface and the flank is in the range of 20 to 26 degrees, and the length of the flank is 1.1 mm or more. The drill cutting edge is brought into contact with the rotating grinding surface of the drill cutting edge, and the rake face and chisel cutting edge of the drill are brought into contact with the flank face, thereby forming the drill cutting edge and the chisel cutting edge. The angle is formed within a range of 154 to 160 degrees.
An inclination angle formed by the drill cutting edge polishing surface and the flank surface is, for example, approximately 22 degrees.

  The inventor has confirmed through experiments that cutting is performed more efficiently than conventional drills if the angle between the drill cutting edge and the chisel cutting edge is in the range of 154 to 160 degrees. This is because, when cutting, the angle change from the chisel cutting edge to the cutting edge eliminates the increase and concentration of the cutting resistance to the cutting edge as compared with the conventional case, and can suppress wear of the cutting edge.

  The grindstone of the present invention is removably fitted to a drill polishing apparatus for polishing a drill in which a drill cutting edge including a rake face and a chisel cutting edge connected to the drill cutting edge are formed. It is a disc-shaped grindstone that provides a surface. An opening for fitting the grindstone to the drill polishing apparatus is formed at the center thereof, and a drill cutting edge polishing surface for polishing the drill cutting edge is formed at the outer peripheral end of the grindstone. A relief surface is formed which communicates with the cutting edge polishing surface and is inclined toward the opening. The inclination angle formed by the drill cutting edge polished surface and the flank is in the range of 20 to 26 degrees, and the length of the flank is 1.1 mm or more. The drill cutting edge is brought into contact with the rotating grinding surface of the drill cutting edge, and the rake face and chisel cutting edge of the drill are brought into contact with the flank face, thereby forming the drill cutting edge and the chisel cutting edge. The angle is formed within a range of 154 to 160 degrees.

  The drill of the present invention has a substantially cylindrical drill body that is formed with a rake face and rotated about an axis, and is provided with a chisel that protrudes from the flank at the tip of the drill body. The angle between the drill cutting edge formed by the flank and the chisel cutting edge connected to the drill cutting edge is 154 to 160 degrees.

  According to the present invention, the angle formed by the drill cutting edge and the chisel cutting edge is formed by forming the inclination angle formed by the grinding surface of the drill cutting edge of the grindstone and the flank within a range of 20 to 26 degrees. It can be formed within the range of 154 to 160 degrees. This angle is a shape that can efficiently cut the spot welded portion by the cutting experiment of the present inventors. The drill polishing apparatus of the present invention can easily perform such drill processing.

It is sectional drawing of a grindstone. It is an enlarged view in a circle of FIG. It is a figure explaining the position of a drill and a grindstone at the time of drill grinding. FIG. 6 is a list of chisel root angles θ and chisel root widths W of samples 1 and 2 and an existing product 1. It is a figure showing the result of the cutting experiment using a drilling machine. It is a graph showing the time and the number of cutting points required for one cutting of a cutting experiment using a drilling machine for each sample. It is a figure showing the result of the cutting experiment using a hand drill. It is a graph showing the time and the number of cutting points required for one cutting of a cutting experiment using a hand drill for each sample. It is a list of the chisel root angle θ and the chisel root width W of samples 3 to 10 and the existing product 2. It is a graph showing the relationship between chisel root angle (theta) and the number of cutting points. It is a graph showing the relationship between chisel root length W and the number of cutting points.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As the drill polishing apparatus of this embodiment, the drill polishing apparatus of Patent Document 1 can be used, but the shape of the grindstone, particularly the shape of the outer peripheral polishing surface, is different.

FIG. 1 is a cross-sectional view of the grindstone 1 of the present embodiment, and FIG. 2 is an enlarged view in a circle of FIG.
The grindstone 1 is disc-shaped, and an opening 10 for fitting in a drill polishing apparatus is provided at the center thereof. The grindstone 1 is fitted into a drill polishing apparatus and rotates.
A polishing surface is formed on the outer periphery of the grindstone 1. The polishing surface includes a drill cutting blade polishing surface 11 for polishing the drill cutting blade, a flank 12 formed in communication with the drill cutting blade polishing surface 11, and a clearance in contact with the drill cutting blade polishing surface 11. An inclined surface 13 for thinning that is formed to be inclined in a direction opposite to the surface 12, and a protruding portion 14 that is formed to protrude from the drill cutting edge polishing surface 11 in communication with the inclined surface 13. .

The inclination angle θ1 formed by the drill cutting edge polishing surface 11 and the flank 12 is formed within a range of 20 to 26 degrees, and the inclination angle θ2 formed by the drill cutting edge polishing surface 11 and the inclined surface 13 is 60, for example. Is set to degrees. The length d of the flank 12 is formed to be 1.1 [mm] or more. Further, the rear end portion of the protrusion 14, that is, the rearmost portion of the grindstone 1 is rounded.
Although the CBN # 170 electrodeposition grindstone is preferably used as the grindstone 1, it is not particularly limited to this.

  The grindstone 1 is fitted into the drill polishing apparatus through the opening 10. For example, a rotating shaft of a motor is attached to the opening 10, and when this rotates, the grindstone 1 rotates to enable the drill to be polished. FIG. 3 is a diagram for explaining the positions of the drill 2 and the grindstone 1 when the drill cutting edge 23 of the drill 2 is polished.

Although not limited to this, the drill 2 is preferably made of high-speed tool steel. The drill 2 has a drill body 20 whose outer shape is substantially cylindrical and rotated about an axis, and a shank portion (not shown) provided at the rear end of the drill body 20 and gripped by the spindle end or the like of a machine tool. It has.
On the outer periphery of the drill body 20, two rake faces 21 formed in a spiral around the axis line are formed from the front end side to the rear end side of the drill body 20.
A flank 22 is provided on the distal end side of the drill body 20, and a drill cutting edge 23 is formed by the rake face 21 and the flank 22. Further, a chisel 24 having a chevron cross section is provided on the tip side of the drill body 20 so as to protrude from the flank 22 substantially in the center when viewed from the axis.

  The chisel 24 and the rake face 21 form a cutting edge (hereinafter referred to as “chisel cutting edge”) 25 connected to the drill cutting edge 23. The chisel cutting edge 25 is provided at a predetermined angle with respect to the drill cutting edge 23 (hereinafter referred to as “chisel root angle θ”). In addition, the width of the base end of the chevron chisel 24 (between the connecting portions of the drill cutting edge 23 and the chisel cutting edge 25) is referred to as a chisel root length in this specification and is represented by “W”.

At the time of polishing, the drill 2 is fixed to a drill grinding table by inserting a shank portion into a drill holder. The drill cutting edge 23 of the drill 2 abuts against the drill cutting edge polishing surface 1 of the grindstone 1 while being fixed to the drill grinding table. Further, the chisel cutting edge 25 of the drill 2 contacts the flank 12. Thus, polishing is performed by bringing the drill 2 and the grindstone 1 into contact with each other.
Since the inclination angle θ1 of the grindstone 1 of the present embodiment is 20 degrees to 26 degrees, the chisel root angle θ of the drill 2 becomes 154 degrees to 160 degrees by polishing. Moreover, since the length d of the flank 12 of the grindstone 1 is 1.1 [mm] or more, it is possible to polish a drill having a chisel root length W of 2.2 [mm] or more. Preferably, the length d of the flank 12 is 1.1 [mm] to 2.5 [mm], and the chisel root length W is 2.2 [mm] to 5.0 [mm]. is there.

  The portion of the chisel 24 where the cutting resistance is concentrated is formed so as to reduce the cutting resistance by thinning. During the thinning process, the shank portion of the drill 2 is fitted into the drill holder and fixed to the drill thinning table. Thinning is performed with a predetermined amount of thinning in the S-type, N-type, X-type, and the like. The thinning process is performed in such a manner that the portion where the cutting resistance of the chisel 24 of the drill 2 is concentrated contacts the inclined surface 13 and the protrusion 14.

  By using a drilling machine and a hand drill, a spot welded portion of a 980 [MPa] steel plate having a thickness of 1.4 [mm] is formed at one location using a drill having a chisel root angle θ of 154 to 160 degrees. The number that can be continuously cut in 15 seconds or less (hereinafter referred to as “the number of cutting points”) was measured.

  FIG. 4 is a list of the chisel root angle θ and the chisel root width W of the drill used in the cutting experiment. Three types of drills used in the experiment, sample 1, sample 2, and existing product 1, are used. Sample 1 is a drill processed by the drill polishing apparatus of this embodiment, and has a chisel root angle of 158 degrees and a chisel root length of 3.6 [mm]. Sample 2 is a drill processed by the drill polishing apparatus of the present embodiment, and has a chisel root angle of 158 degrees and a chisel root length of 4.6 [mm]. The existing product 1 is a drill processed by an existing drill polishing apparatus, and has a chisel root angle of 143 degrees and a chisel root length of 2.8 [mm].

FIG. 5 is a diagram showing the results of a cutting experiment using a drilling machine. FIG. 6 is a graph showing the time and the number of cutting points required for one cutting operation for each sample in a cutting experiment using a drilling machine. If the cutting time takes 15 seconds or more, the cutting process is terminated.
The drill of sample 1 had 60 cutting points, the drill of sample 2 had 68 cutting points, and the existing product 1 had 20 cutting points.

FIG. 7 is a diagram illustrating a result of a cutting experiment using a hand drill. FIG. 8 is a graph showing the time and number of cutting points required for one cutting operation for each sample in a cutting experiment using a hand drill. As in the case of using a drilling machine, when the cutting time takes 15 seconds or more, the cutting process is terminated.
The drill of sample 1 had 46 cutting points, the drill of sample 2 had 60 cutting points, and the existing drill had 7 cutting points.

  From these results, it can be seen that the larger the chisel root angle θ and the chisel root length W, the larger the number of cutting points, which is suitable for cutting. In addition, the performance of both samples 1 and 2 is abruptly deteriorated, and the time required for the cutting process becomes abruptly increased or cutting cannot be performed.

  FIG. 9 is a list of the chisel root angle θ and the chisel root width W of the drill used in the cutting experiment for obtaining the range of appropriate values of the chisel root angle θ and the chisel root length W. Nine types of samples 3 to 10 and existing product 2 are used for the drill used in the experiment. Samples 3 to 5 and Samples 8 to 10 have a chisel root angle of 154 to 160 degrees and a chisel root length of 2.2 [mm] to 5.0 [mm]. Samples 6 and 7 have chisel root angles of 146 degrees and 142 degrees and chisel root lengths of 2.1 [mm] and 2.7 [mm], respectively. The existing product 2 has a chisel root angle of 146 degrees and a chisel root length of 2.8 [mm]. The experimental conditions are the same as those of the experiments of FIGS. 7 and 8, and only the samples are different.

  As a result of the experiment, the sample 3 drill has 21 cutting points, the sample 4 drill has 25 cutting points, the sample 5 drill has 38 cutting points, the sample 6 drill has 0 cutting points, the sample 7 The number of cutting points is 12 for the drill of No. 8, the number of cutting points of 19 for the drill of Sample 8, the number of cutting points of 27 for the Drill of Sample 9, the number of cutting of 44 for the Drill of Sample 10, and the number of cutting for the Drill of the existing product 2 Became 3 points.

FIG. 10 is a graph showing the relationship between the chisel root angle θ and the number of cutting points. FIG. 11 is a graph showing the relationship between the chisel root length W and the number of cutting points.
As is clear from these graphs, the chisel root angle θ is between 154 and 160 degrees, and the chisel root length W is between 2.2 [mm] and 5 [mm], which is significantly larger than the existing products. The number of cutting points has increased. The chisel root angle θ is 154 degrees or more, and the number of cutting points tends to increase as it increases.

The drill with the chisel root angle θ in the range of 154 to 160 degrees and the chisel root length W in the range of 2.2 [mm] to 5 [mm] is a high-strength steel plate. Even if it exists, it becomes possible to suppress the abrasion of the drill cutting edge 23 and to perform a cutting process continuously in a short time to many spot weld parts conventionally. Therefore, cutting can be performed much more efficiently than before, and the labor of the operator can be suppressed.
Therefore, if the inclination angle θ1 of the grindstone 1 is 20 to 26 degrees and the length d of the flank 12 is 1.1 [mm] or more, such a drill can be easily processed.

  Note that the chisel root angle θ and the chisel root length W of each sample used in the cutting experiment are not exactly the above values but have variations due to the limit of machining accuracy. Therefore, for example, even if the chisel root angle θ in FIG. 4 is 158 degrees, it is not exactly 158 degrees in practice. For the same reason, the inclination angle θ1 of the grindstone 1 is not exactly 22 degrees, but is approximately 22 degrees.

  DESCRIPTION OF SYMBOLS 1 ... Grinding stone, 10 ... Opening part, 11 ... Drill cutting edge grinding | polishing surface, 12 ... Flank, 13 ... Inclined surface, 14 ... Projection part, 2 ... Drill, 20 ... Drill main body, 21 ... Rake face, 22 ... Flank 23 ... Drill cutting edge, 24 ... Chisel, 25 ... Chisel cutting edge

Claims (4)

A drill polishing apparatus that performs polishing by bringing a drill formed of a drill cutting edge including a rake face and a chisel cutting edge connected to the drill cutting edge into contact with a polishing surface of a rotating grindstone,
The polished surface is
A drill cutting edge polishing surface for polishing the drill cutting edge;
A flank formed in communication with the drill cutting edge polishing surface,
An inclination angle formed by the drill cutting edge polished surface and the flank surface is within a range of 20 degrees to 26 degrees;
The length of the flank is 1.1 [mm] or more,
The drill cutting edge is brought into contact with the rotating grinding surface of the drill cutting edge, and the rake face and chisel cutting edge of the drill are brought into contact with the flank face, thereby forming the drill cutting edge and the chisel cutting edge. Forming an angle within a range of 154 to 160 degrees;
Drill polishing equipment. An inclination angle formed by the drill cutting edge polishing surface and the flank is approximately 22 degrees.
The drill polishing apparatus according to claim 1. A disc shape that is removably fitted to a drill polishing device that polishes a drill formed with a drill cutting edge including a rake face and a chisel cutting edge connected to the drill cutting edge, and provides a polishing surface by rotating during use. The whetstone of
An opening for fitting to the drill polishing apparatus is formed at the center,
A drill cutting edge polishing surface for polishing the drill cutting edge and a flank face formed in an inclined manner toward the opening portion in communication with the drill cutting edge polishing surface are formed at the outer peripheral end portion. And
An inclination angle formed by the drill cutting edge polished surface and the flank surface is within a range of 20 degrees to 26 degrees;
The length of the flank is 1.1 [mm] or more,
The drill cutting edge is brought into contact with the rotating grinding surface of the drill cutting edge, and the rake face and chisel cutting edge of the drill are brought into contact with the flank face, thereby forming the drill cutting edge and the chisel cutting edge. Forming an angle within a range of 154 to 160 degrees;
Whetstone for drill polishing equipment. It has a generally cylindrical drill body with a rake face formed and rotated around an axis,
A chisel is provided to protrude from the flank at the tip of this drill body,
The angle formed by the drill cutting edge formed by the rake face and the flank and the chisel cutting edge connected to the drill cutting edge is 154 to 160 degrees.
drill.

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