JP4385642B2 - Hammer drill bit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drill bit for a hammer drill, and more particularly to a drill bit for a hammer drill attached to an electric hammer drill for making a hole in concrete or the like.
[0002]
[Prior art]
Conventionally, a drill bit is provided in an electric hammer drill for drilling a hole in concrete or rock. The drill bit includes a drill shaft having a drill head at a tip thereof. A tip for making a hole is provided at the tip of the drill head. The tip is made of cemented carbide and is joined to the tip of the drill head by brazing. The drill bit is attached to an electric hammer drill body. The drill bit is configured to be able to perform drilling by reciprocating in the axial direction of the drill shaft at the same time as the drill bit rotates by the rotational force and impact force transmitted from the hammer drill body.
[0003]
Drill bits are required to improve the drilling speed when drilling holes, suppress vibration during drilling, and improve the roundness of holes formed by drilling. In order to improve the drilling speed, it is necessary to quickly discharge the drilling powder from the drilled hole so as not to prevent the contact between the concrete and the chip forming the part to be drilled from now on.
[0004]
In addition, the vibration of the drill bit during drilling has an adverse effect on the operator and becomes a factor that hinders long-time work. In addition, the vibration of the drill bit during drilling means that the tip of the drill bit is shaken during drilling, and has an adverse effect on the roundness of the hole to be drilled. Therefore, it is necessary to suppress the occurrence of vibration as much as possible. Whether or not the requirements for the drill bit as described above can be satisfied greatly depends on the shape of the tip portion of the drill bit. For this reason, drill bits that are devised in terms of the number, shape and arrangement of tips and the shape of the drill head are used.
[0005]
GB GB 2075409 describes a drill bit for a hammer drill that meets this requirement. As shown in FIG. 6, the drill bit 102 includes a drill shaft 121 having a drill head 122 at a tip that forms one end, and is rotatable about its axis. The other end (not shown) of the drill shaft 121 is attached to a hammer drill body (not shown). At the tip of the drill head 122, chips 123 and 124 that form blades for making holes in concrete or the like are provided. On the side surface of the drill shaft 121, two spiral grooves 121 a and 121 b are formed from the drill head 122 toward the axial direction of the drill shaft 121.
[0006]
The chips 123 and 124 are composed of a main chip 123 and a sub chip 124. The main tip 123 is composed of main tip blades 123A and 123B that extend across the outer peripheral surface of the drill head 122 so that the tip of the drill head 122 crosses the tip of the drill head 122 in a straight line in the diameter direction of the drill head 122. ing. Further, the sub chip 124 is constituted by two sub chip blades 124A and 124B. The two sub-tip blades 124A and 124B are arranged on the same straight line passing through the axis of the drill shaft 121 and the drill head 122 at the tip of the drill head 122, and extend perpendicular to the main tip blades 123A and 123B. Has been. One sub-tip blade 124A is located on one side of the tip of the drill head 122 divided into two by the main tip blades 123A and 123B, and the other sub-tip blade 124B is located on the other side of the tip of the drill head 122.
[0007]
The main chip 123 and the sub chip 124 are arranged at a predetermined interval in the rotation direction of the drill head 122, and four inter-chip spaces 122 a to 122 d are formed by the main chip 123 and the sub chip 124 at the tip of the drill head 122. It is defined. The drill head 122 is formed with a total of four discharge grooves, which are discharge grooves 122e and 122f communicating with the four inter-chip spaces 122a to 122d, respectively, and two discharge grooves (not shown), and the four inter-chip spaces 122a to 122d. Two of them 122a and 122b communicate with one spiral groove 121a via discharge grooves 122e and 122f, and the remaining two inter-chip spaces 122c and 122d are connected to each other via two remaining discharge grooves (not shown). It communicates with the spiral groove 121b.
[0008]
The formation of the four discharge grooves improves the discharge capability of drilling powder generated during drilling, and loss of rotational force and striking force transmitted from the motor provided in the hammer drill body (not shown) to the drill bit 102. This is to reduce as much as possible and increase the drilling speed. Another reason is to suppress the occurrence of vibration in the drill bit 102 by discharging the drilling powder and to improve the accuracy of the hole to be drilled. The drill bit 102 described in this publication optimizes the shape and arrangement of the discharge grooves, improves the discharge capability of the drilling powder by drilling, and improves the performance required for the drill bit as described above.
[0009]
[Patent Document 1]
British Patent GB 2075409 (FIGS. 1-2)
[0010]
[Problems to be solved by the invention]
In the conventional drill bit 102 described above, two discharge grooves 122e and 122f are connected to and communicate with one spiral groove 121a, and the spiral groove 121a has a predetermined angle with respect to the axis of the drill bit 102. Therefore, as shown in FIG. 6, one connection position 121d of the two connection positions 121d and 121e of the one spiral groove 121a and the two discharge grooves 122e and 122f is the other connection position. The positional relationship is closer to the tip of the drill shaft 121 than 121e.
[0011]
When drilling, as shown by the arrow C in FIG. 6, the drilling powder is sent from the two discharge grooves 122e and 122f to the spiral groove 121a, but from the discharge groove 122f to the spiral groove 121a. The sent drilled powder passes through the other connection position 121e in the spiral groove 121a. When the tip of the drill bit 102 is drilled in a vertically downward direction, that is, when the drill bit 102 is drilled in such a positional relationship that the top is vertically upward and the bottom is vertically downward, it is a part of the spiral groove 121a. At the other connection position 121e, a hole made of a discharge groove 122e directed vertically downward is formed.
[0012]
At this time, the drilling powder is also sent from the discharge groove 122e into the spiral groove 121a. However, if the amount sent is small, the drilling powder sent from the discharge groove 122f is connected to the other connection position 121e. A space for dropping into the discharge groove 122e is formed when passing through. When the perforated powder falls into the inter-chip space 122a through this space, the discharge efficiency of the perforated powder decreases. As a result, the drilling speed is reduced and the drill bit 102 is vibrated. Such a phenomenon is particularly likely to occur when drilling of a hard material generates little drilling powder. The same applies to two connection positions (not shown) of the other spiral grooves 121b.
[0013]
In order to prevent the perforated powder from falling into the discharge groove 122e, the entire discharge groove 122e may be filled, and the discharge groove 122e may not be formed. The space in which the drilling powder scraped by the chips 123 and 124 can flow at the tip of the drill head 122 is narrowed, leading to clogging of the drilling powder, and the drilling speed is reduced.
[0014]
Thus, the present invention prevents the drilling powder from falling into the space between the chips through the discharge groove, improves the drilling speed, suppresses vibration during drilling, and is a perfect circle of the hole formed by drilling. An object of the present invention is to provide a drill bit for a hammer drill capable of improving the degree.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a drill shaft that has a drill head at the tip and rotates around an axis, and a tip that is provided at the tip of the drill head and forms a blade for making a hole. And at least one spiral groove in the axial direction of the drill shaft is formed on a side surface of the drill shaft and closer to the base end of the drill shaft than the drill head , A main tip and a sub tip, the main tip and the sub tip are arranged at a predetermined interval in the rotation direction of the drill shaft, and a plurality of the main tip and the sub tip at the tip of the drill head. inter-chip space is defined, the main chip protrudes than the sub chip in the axial direction of the drill shaft, a the side of the drill head A position between the tip and the spiral groove of the drill head, as many discharge groove of the inter-chip spaces respectively communicating with the inter-chip spaces are formed, at least two of the plurality of inter-chip spaces Is a drill bit that communicates with the one spiral groove through the discharge groove, and is located behind the rotation direction of the main chip in the connection position with the spiral groove in the discharge groove that communicates with the one spiral groove. At the connection position of the discharge groove adjacent to the main chip with the spiral groove, a convex part is provided to partially block the communication of the discharge groove to the spiral groove, and is cut off by the main chip. A drill bit for a hammer drill is provided in which drilling powder is sent to the discharge groove adjacent to the main tip in front of the main tip in the rotation direction.
[0016]
Here, the main tip consists of a main tip blade that extends across the tip of the drill head in a straight line in the diameter direction of the drill shaft and whose both ends extend beyond the outer peripheral surface of the drill head, The sub-tip is composed of two sub-tip blades, and the two sub-tip blades are arranged on the same straight line passing through the axis of the drill shaft at the tip of the drill head and extend perpendicular to the main tip blade. One of the sub-tip blades is located on one side of the tip of the drill head divided by the main tip blade, and the other sub-tip blade is located on the other side of the tip of the drill head. The sub-tip blades are preferably arranged so as to be spaced apart from the main tip blade.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
A drill bit of a hammer drill according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the drill bit of the hammer drill is attached to the tip of the electric hammer drill main body 1, that is, the lower end position shown in FIG. 1 of the electric hammer drill main body 1. The drill bit 2 has a drill shaft 21 in which a drill head 22 is integrally provided at a tip that constitutes one end thereof, and the other end is driven and connected to a motor (not shown) provided in the electric hammer drill main body 1. Yes. The drill bit 2 is rotated about the axis of the drill shaft 21 by a rotational force and a hitting force transmitted from a motor (not shown), and at the same time, the drill bit 2 is reciprocated in the axial direction of the drill shaft 21 to perform drilling. It is configured to be able to. The drill head 22 and the drill shaft 21 are made of structural alloy steel made of JIS: SNCM630.
[0018]
As shown in FIGS. 2 to 4, tips 23 and 24 that form blades for drilling holes in concrete or the like are provided at the tip of the drill head 22. The chips 23 and 24 are made of a cemented carbide made of WC (tungsten carbide) and Co (cobalt), and are joined to the tip of the drill head 22 by brazing. On the side surface of the drill shaft 21, two spiral grooves 21a and 21b are formed in the axial direction of the drill shaft 21 (FIG. 1). Each of the two spiral grooves 21a and 21b is located at a predetermined position toward the other end of the drill shaft 21 with a position closer to the other end by a predetermined distance from the tip forming one end of the drill head 22 as a starting point 21c. The starting point 21c, which is the two starting points of the two spiral grooves 21a and 21b, and the starting point (not shown) are located at both ends of the diameter of the drill head 22. Accordingly, the two spiral grooves 21a and 21b are double spirals whose phases are shifted by 180 °, and the two spiral grooves 21a and 21b are formed on the drill shaft 21 as shown in FIGS. It appears alternately in the axial direction.
[0019]
The chips 23 and 24 are constituted by a main chip 23 and a sub chip 24. As shown in FIG. 3, the main tip 23 extends across the outer peripheral surface 22 </ b> C of the drill head 22 so as to cross the tip of the drill head 22 in a straight line in the diameter direction of the drill shaft 21. It consists of main tip blades 23A and 23B. More specifically, the main chip 23 is composed of two main chip blades 23A and 23B as shown in FIG. 3A, and the two main chip blades 23A and 23B are flush with each other and the direction of the blades. Are arranged so as to be reversed, and the respective edge portions 23C are connected to each other, and are configured as if they were one blade. The edge portions 23 </ b> C connected to each other coincide with the positions of the axial centers of the drill shaft 21 and the drill head 22.
[0020]
The subchip 24 is composed of two subchip blades 24A and 24B. The two sub-tip blades 24A and 24B are arranged on the same straight line passing through the axis of the drill shaft 21 at the tip of the drill head 22, and extend perpendicular to the main tip blades 23A and 23B. One sub tip blade 24A is located on one side of the tip of the drill head 22 divided by the main tip blades 23A and 23B, that is, on the upper side in FIG. 3A, and the other sub tip blade 24B is located on the drill head 22. It is located on the other side of the tip, that is, on the lower side of FIG. The two sub-chip blades 24A and 24B are arranged at a predetermined distance from the main chip blades 23A and 23B, respectively. For this reason, drilling powder can freely pass through the plurality of inter-chip spaces 22a to 22d during drilling.
[0021]
As shown in FIG. 3, the main chip 23 and the two sub chips 24 are arranged at a predetermined interval in the rotation direction of the drill shaft 21. For this reason, four inter-chip spaces 22 a to 22 d are defined in the rotation direction of the drill shaft 21 by the main tip 23 and the sub-tip 24 at the tip of the drill head 22. Four discharge grooves 22e to 22h communicating with the four inter-chip spaces 22a to 22d are formed on the side surface of the drill head 22 between the tip of the drill head 22 and the spiral grooves 21a and 21b. Yes. Of the four inter-chip spaces 22a to 22d, two 22a and 22b communicate with one spiral groove 21a via discharge grooves 22e and 22f, and the remaining two inter-chip spaces 22c and 22d are the remaining two It communicates with the other spiral groove 21b through the discharge grooves 22g and 22h (FIG. 3A).
[0022]
Of the discharge grooves 22e and 22f communicating with the one spiral groove 21a, the connection positions 21d and 21e (FIG. 3B) with the spiral groove 21a that are located closest to the tip of the drill shaft 21 are excluded. A convex portion 22A is provided at the connection position 21e. Similarly, in the discharge grooves 22g and 22h (FIG. 3 (a)) communicating with the other spiral groove 21b, the position closest to the tip of the drill shaft 21 among two connection positions (not shown) with the spiral groove 21b. Convex portions 22B (FIG. 3 (a)) are also provided at connection positions (not shown) excluding those to be performed.
[0023]
The convex portions 22A and 22B protrude to a position that coincides with the outer peripheral surface 22C of the drill head 22, and have a shape in which the discharge grooves 22e and 22g are covered at the connection position 21e and a connection position (not shown). . As described above, since both ends of the main tip 23 extend beyond the outer peripheral surface 22C of the drill head 22 as shown in FIG. 3A, holes formed by the main tip 23 during drilling are provided. The inner peripheral surface is separated from the outer peripheral surface 22 </ b> C of the drill head 22. For this reason, even if the convex portions 22A and 22B are provided, the discharge grooves 22e and 22g are not completely closed, and the convex portions 22A and 22B are connected to the spiral grooves 21a and 21b of the discharge grooves 22e and 22g. Is partially blocked.
[0024]
For this reason, when the drilling powder sent from the discharge groove 22f to the spiral groove 21a during drilling passes through the connection position 21e in the spiral groove 21a, the drilling powder is prevented from falling into the discharge groove 22e. Therefore, it is possible to increase the discharge efficiency of the drilling powder, reduce the energy transmission loss, and improve the drilling speed. Further, vibration during drilling can be suppressed. Thereby, the roundness of the hole formed by perforation can be improved.
[0025]
Further, since the discharge grooves 22e and 22g are not filled and the space defined by the discharge grooves 22e and 22g is still left, the flow of drilling powder at the tip of the drill head 22 can be promoted. For this reason, clogging of the drilling powder in the inter-chip spaces 22a to 22d can be suppressed, the discharge efficiency can be improved, and the drilling speed and the occurrence of vibration can be improved.
[0026]
At the time of drilling, as shown in FIG. 4, when the drilling powder 4 generated by scraping the concrete wall 3 by the main chip 23 increases at the tip of the drill head 22, it is indicated by an arrow A in FIG. 1 or 4. It is sent from the discharge groove 22f to the spiral groove 21a in the direction and wound up in a direction approaching the hammer drill body along the spiral groove 21a. The perforated powder 4 reaches the connection position 21e. Since the protrusion 22A is provided at the connection position 21e, the drilling powder 4 continues to move along the spiral groove 21a without falling into the discharge groove 22e. Similarly, the perforated powder 4 is discharged at a connection position (not shown) between the discharge grooves 22g and 22h (FIG. 3 (a)) and the spiral groove 21b and provided with a convex portion 22B. The connection position continues to move along the spiral groove 21b without falling into the groove 22g. Further, the perforated powder 4 is stirred and flows in a vortex as shown by an arrow B in FIG. 4 in the discharge groove 22e provided with the convex portions 22A.
[0027]
Next, a test was performed using the drill bit 2 of the hammer drill according to the present embodiment. In the experiment, the hammer bit drill bit 2 according to the present embodiment was used as the product of the present invention. Further, as the conventional product, one in which the protruding portions 22A and 22B are not provided in the discharge grooves 22e and 22g of the drill bit 2 of the hammer drill according to the present embodiment is used. Further, as a comparative product, a product in which all the discharge grooves 22e and 22g provided with the convex portions 22A and 22B of the drill bit 2 of the hammer drill according to the present embodiment are filled is used. These drill bits were attached to the hammer drill body 1 and tested by drilling in the concrete wall. The product of the present invention, the conventional product, and the comparative product all have a bit diameter of 40 mm, a rotational speed of 330 / min, and a hitting speed of 2700 / min.
[0028]
The test results are as shown in the graph of FIG. The comparative product has a slightly higher drilling speed than the conventional product, but the drilling speed of both the conventional product and the comparative product is less than 50 mm / min. In contrast, in the product of the present invention, the drilling speed is about 60 mm / min, which is about 16% higher than that of the comparative product and 17% higher than that of the conventional product. From this test result, it can be understood that the drill bit 2 according to the present embodiment has a significantly improved drilling speed due to the provision of the convex portions 22A and 22B.
[0029]
The drill bit of the hammer drill according to the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope described in the claims. For example, in this embodiment, two spiral grooves are formed, but the number is not limited to this. It is sufficient that at least one is formed. Further, the number of main chips, sub chips, inter-chip spaces, and discharge grooves is not limited to the number according to the present embodiment.
[0030]
Moreover, you may change the magnitude | size of a convex part according to the hardness of a to-be-punched material. Even if the amount of drilled powder differs due to the hardness of the material to be punched, by making the convex part an appropriate size, it is possible to achieve a good balance between the discharge of drilled powder and the prevention of falling, and the discharge performance Can be increased. From the same point of view, it is not necessary to provide convex portions at all the connection positions except the one located closest to the tip of the drill shaft among the connection positions with the spiral groove in the discharge groove communicating with the spiral groove. An appropriate number of protrusions may be provided. Moreover, although the convex part had the shape which covers a discharge groove in the connection position with the spiral groove of a discharge groove, it is not limited to this shape. For example, you may comprise a convex part thicker than the thing of this Embodiment.
[0031]
【The invention's effect】
According to the drill bit of the hammer drill according to claim 1, the discharge adjacent to the main tip at the rear in the rotation direction of the main tip in the connection position with the spiral groove in the discharge groove communicating with the one spiral groove. At the connection position of the groove with the spiral groove, a convex portion is provided to partially prevent the discharge groove from communicating with the spiral groove, so that when the drilled powder passes through the connection position in the spiral groove The perforated powder can be prevented from falling into the discharge groove, the efficiency of discharging the perforated powder can be increased, the transmission loss of energy can be reduced, and the perforation speed can be improved. Further, vibration during drilling can be suppressed. Thereby, the roundness of the hole formed by perforation can be improved.
[0032]
Further, since the discharge groove is not filled and a space defined by the discharge groove is still formed, the flow of the drilling powder in the discharge groove can be promoted. For this reason, clogging of the drilling powder in the space between the chips can be suppressed, the discharge efficiency can be improved, and the drilling speed and the generation of vibration can be improved.
[0033]
According to the drill bit of the hammer drill according to the second aspect, since the two sub-tip blades are spaced apart from the main tip blade, the drilling powder can freely travel through the spaces between the plurality of tips.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state in which a drill bit of a hammer drill according to an embodiment is attached to a hammer drill body.
FIG. 2 is a perspective view showing a drill head of a drill bit of a hammer drill according to the present embodiment.
3A and 3B are diagrams showing a drill head of a drill bit of a hammer drill according to the present embodiment, where FIG. 3A is a front view, and FIG. 3B is a side view.
FIG. 4 is a conceptual diagram showing movement of drilling powder in a drill head of a drill bit of a hammer drill according to the present embodiment.
FIG. 5 is a graph showing a test result of the drill bit of the hammer drill according to the present embodiment.
FIG. 6 is a perspective view showing a drill head of a drill bit of a hammer drill according to a conventional embodiment.
[Explanation of symbols]
2 ... Drill bit 21 ... Drill shaft 21a, 21b ... Spiral groove 21d, 21e ... Connection position 22 ... Drill head 22A, 22B ... Convex part 22a-22d ... Between chips Space 22e to 22h ... discharge groove 23 ... main tip 23A, 23B ... main tip blade 24 ... sub tip 24A, 24B ... sub tip blade

Claims (2)

A drill shaft having a drill head at the tip and rotating about the axis; and
A tip which is provided at the tip of the drill head and forms a blade for making a hole;
At least one spiral groove is formed in the side surface of the drill shaft and closer to the base end of the drill shaft than the drill head , in the axial direction of the drill shaft,
The tip includes a main tip and a sub tip, and the main tip and the sub tip are arranged at a predetermined interval in the rotation direction of the drill shaft, and the main tip and the sub tip are arranged at the tip of the drill head. A plurality of inter-chip spaces are defined by the main chip, which protrudes from the sub-chip in the axial direction of the drill shaft,
On the side surface of the drill head and between the tip of the drill head and the spiral groove, the same number of discharge grooves as the number of inter-chip spaces communicating with the inter-chip spaces are formed, and a plurality of chips In a drill bit in which at least two of the interspaces communicate with one spiral groove through the discharge groove,
Of the connection positions with the spiral groove in the discharge groove communicating with the one spiral groove, at the connection position with the spiral groove of the discharge groove adjacent to the main chip at the rear in the rotation direction of the main chip. Is provided with a convex portion that partially prevents the discharge groove from communicating with the spiral groove, and the drilled powder scraped off by the main chip is adjacent to the main chip in the rotation direction of the main chip. A drill bit for a hammer drill, characterized by being fed into a groove. The main tip is composed of a main tip blade extending in a straight line across the tip of the drill head in the diameter direction of the drill shaft and extending at both ends beyond the outer peripheral surface of the drill head,
The sub-tip is composed of two sub-tip blades, and the two sub-tip blades are arranged on the same straight line passing through the axis of the drill shaft at the tip of the drill head and extend perpendicular to the main tip blade. One of the sub-tip blades is located on one side of the tip of the drill head divided by the main tip blade, and the other sub-tip blade is located on the other side of the tip of the drill head. 2. The drill bit of a hammer drill according to claim 1, wherein the sub-tip blades are arranged apart from the main tip blade.

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