Drill bit body

Abstract

A main body capable of suppressing deflection during machining is provided. The main body 100 includes a first mounting portion 101 provided at a front end side and being a portion where a cutting edge 210 is mounted, and a second mounting portion 102 provided at a position different from the first mounting portion 101 in the circumferential direction at the front end side and being a portion where a guide pad 300 is mounted. An exhaust groove 111 is formed in an outer peripheral surface of the main body 100, is a groove extending from the front end side to a base end side, and functions to guide and exhaust fluid to the base end side. At least a portion of the exhaust groove 111 is curved.

Description

Technical Field

[0001] This invention relates to a drill bit body. Background Technology

[0002] Drill bits are known as tools for forming small-diameter deep holes. A drill bit has a cutting edge at the front end of its slender body. Typically, only one cutting edge is provided, or multiple cutting edges are provided at asymmetrical positions around the axis of rotation. This structure results in a force applied to the cutting edge in an off-direction during machining. Therefore, as described in Patent Document 1 below, a guide pad is usually provided at the front end of the drill bit's body. During machining, the guide pad abuts against the inner surface of the hole in the material being cut, thus suppressing deformation of the drill bit body caused by the aforementioned force.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2019-104102

[0006] Technical issues

[0007] During machining, the forces on the cutting edge and the forces on the guide pad are applied at different locations along the longitudinal direction of the main body. Therefore, the forces do not cancel each other out and become zero, and a bending moment is applied to the main body to cause it to flex into an arc shape.

[0008] The main body has a groove for discharging coolant. If the direction in which the longitudinal center of the main body will shift due to the aforementioned bending moment coincides with the bending direction in which the secondary moment of the cross-section decreases as the groove is formed, the main body will deflect significantly during machining. As a result, a portion of the main body will come into contact with the inner surface of the machined hole, potentially leading to a reduction in machining accuracy.

[0009] The purpose of this invention is to provide a body capable of suppressing deflection during the processing. Summary of the Invention

[0010] The main body of this invention is a drill bit body, comprising: a first mounting part disposed on the front end side, which is a part for mounting the cutting edge; and a second mounting part disposed circumferentially on the front end side at a different position from the first mounting part, which is a part for mounting the guide pad. A discharge groove is formed on the outer circumferential surface of the main body, extending from the front end side to the base end side, for guiding fluid towards the base end side and discharging it; at least a portion of the discharge groove is curved.

[0011] In the main body of the above structure, due to the bending of at least a portion of the discharge groove, the direction in which the longitudinal central part of the main body wants to shift due to the bending moment during processing is different from the bending direction in which the secondary moment of the cross-section decreases as the groove is formed. Therefore, compared with the past, the deflection of the main body during processing can be suppressed.

[0012] As a more preferred approach, at least a portion of the discharge groove may bend towards the opposite side of the rotation direction as it gets closer to the base side from the front end side.

[0013] Alternatively, when viewed along the rotation center axis, the angle change of the inner surface of the discharge groove is within 40 degrees as the position changes from the front end to the base end.

[0014] As a more preferred embodiment, the proportion of the discharge groove in the cross section when the portion near the base end is cut perpendicularly relative to the rotation center axis may be 20% or more, relative to the portions near the first mounting portion and the second mounting portion.

[0015] Alternatively, a more preferred method is to arrange multiple second mounting parts in a circumferential manner.

[0016] According to the present invention, a body capable of suppressing deflection during processing is provided. Attached Figure Description

[0017] Figure 1 This is a perspective view showing the overall structure of the drill bit according to this embodiment.

[0018] Figure 2 This is a perspective view showing the overall structure of the drill bit according to this embodiment.

[0019] Figure 3 This is a diagram depicting the drill bit of this embodiment as viewed from the front end along its rotational axis.

[0020] Figure 4 yes Figure 1 An enlarged schematic diagram of a portion thereof.

[0021] Figure 5 yes Figure 2 An enlarged schematic diagram of a portion thereof.

[0022] Figure 6 This is a diagram used to illustrate the forces applied to the body of the comparative example during the processing.

[0023] Figure 7 This is a diagram used to illustrate the forces applied to the body of the comparative example during the processing.

[0024] Figure 8 This diagram illustrates the forces applied to the main body of this embodiment during the manufacturing process.

[0025] Figure 9 It is a diagram showing the relationship between the torsion angle of the groove and the displacement of the central part of the main body.

[0026] Explanation of main component symbols

[0027] Detailed Implementation

[0028] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding, the same symbols will be used to label the same components as much as possible in the drawings, and repeated descriptions will be omitted.

[0029] The structure of the drill bit 10 in this embodiment will be described. Figure 1 and Figure 2 This is a perspective view showing the overall structure of drill bit 10. Figure 3 yes Figure 1 The diagram depicts the drill bit 10 as viewed from the front end side along its rotational axis AX. Figure 4 yes Figure 1 An enlarged schematic diagram of a portion thereof, specifically an enlarged schematic diagram of the front end portion of drill bit 10. Figure 5 yes Figure 2 An enlarged schematic diagram of a portion thereof, specifically an enlarged schematic diagram of the front end portion of drill bit 10.

[0030] like Figure 1 As shown, the drill bit 10 includes a body 100, a cutting blade 200, and a guide pad 300.

[0031] The main body 100 is a component that constitutes the general whole of the drill bit 10 and is made of steel. The main body 100 has a holding part 120 and a cutting part 110. The holding part 120 is a part along the longitudinal direction of the main body 100 and is held by a machine tool (not shown).

[0032] For ease of explanation, one end side of the main body 100 is provided with the gripped portion 120, which will also be referred to as the "base end side" below. In addition, the side opposite to the base end side will also be referred to as the "front end side" below.

[0033] The cutting portion 110 is the part of the main body 100 closer to the front end than the gripped portion 120, and is used for cutting the material being cut. The cutting portion 110 is formed to extend linearly from the gripped portion 120 towards the front end. Figure 3As shown, the cutting portion 110 is slightly cylindrical, with a discharge groove 111 formed on its side. The discharge groove 111 is a groove that guides and discharges coolant during machining, and is formed to extend from the front end side to the base end side. The coolant is a fluid supplied from the machine tool side during machining for purposes such as discharging chips, cooling tools and cut materials, lubrication, and rust prevention. The discharge groove 111 is not a straight line extending entirely along the longitudinal direction of the cutting portion 110; a portion of it (in...) Figure 5 The portion marked "G2" is curved. The reason for this structure will be explained below.

[0034] The cutting insert 200 is the portion having a cutting edge 210 and is formed of a superhard material. The cutting insert 200 is fastened and fixed to the inner surface of the discharge groove 111 near the end on the front end side by screws 11. In addition, on the front end side of the main body 100, each portion corresponding to the cutting insert 200 is provided with a mounting portion 101 (mounting seat) for mounting the cutting insert 200, and the cutting insert 200 is mounted on each mounting portion 101. The mounting portion 101 corresponds to the "first mounting portion" in this embodiment.

[0035] The cutting edge 210 of the cutting insert 200 protrudes further from the front end of the cutting section 110 towards the front end side. When machining the workpiece, the main body 100 rotates about the rotation center axis AX. Its rotation direction is the direction in which the chips generated during machining abut against the rake face of the cutting insert 200; specifically, it is... Figure 3 The direction indicated by the middle arrow. When the main body 100 rotates, the material being cut is cut by contacting the cutting edge 210, thereby forming a deep hole in the material being cut. In the drill bit 10 of this embodiment, as described above, the cutting edge 210 portion is a replaceable independent component, constituting a so-called "tip-replaceable" tool. Alternatively, the cutting edge 210 portion can also be brazed to the main body 100 to form an integral structure.

[0036] In this embodiment, the body 100 of the drill bit 10 is a so-called "single flute-shaped" tool, forming only one discharge groove 111. Correspondingly, only one cutting edge 210 is provided.

[0037] The guide pad 300 is a component that suppresses deformation of the main body 100 by abutting against the inner surface of the hole during machining. The hole formed in the workpiece by the drill bit 10 is also referred to below as a "machined hole". By providing the guide pad 300, machining can be performed while ensuring the straightness and roundness of the machined hole. Furthermore, on the front end side of the main body 100, a mounting portion 102 (recess) for mounting the guide pad 300 is provided at a portion corresponding to the guide pad 300, and the guide pad 300 is mounted on each mounting portion 102. The mounting portions 102 are located at positions different from mounting portions 101 along the circumferential direction. The mounting portion 102 corresponds to the "second mounting portion" in this embodiment.

[0038] In this embodiment, where the cutting edge 210 is only located at one point in the circumferential direction, a deflection force will be applied to the cutting edge 210 during machining. Therefore, by providing a guide pad 300 at a location capable of withstanding this force, deformation of the main body 100 during machining can be suppressed, and as described above, the straightness and roundness of the machined hole can be ensured.

[0039] like Figure 4 As shown, a guide pad 300 is mounted on the outer circumferential surface of the cutting part 110 near the end of the cutting part 110 (however, at a position different from the cutting edge 210 along the circumferential direction). In this embodiment, two guide pads 300 are provided, arranged circumferentially. Each guide pad 300 is fastened to the cutting part 110 by a screw 12, which serves as a fastening component. Furthermore, the number of guide pads 300 mounted on the cutting part 110 can be one or more.

[0040] like Figure 4 As shown, in the cutting section 110, a discharge hole 112 and a groove 113 are formed near the portion where the guide pad 300 is installed.

[0041] The discharge hole 112 is a hole used to supply coolant during machining. A flow path (not shown) for guiding coolant is formed inside the main body 100. One end of this flow path opens at the base end of the holding portion 120. The discharge hole 112 is an opening formed at the other end of this flow path. During machining, coolant is supplied from the machine tool to the flow path. The coolant is discharged through the discharge hole 112 via the flow path and then flows into the tank 113.

[0042] The groove 113 is formed along the outer peripheral surface of the cutting portion 110, and is used to guide the coolant discharged from the discharge hole 112 to the cutting edge 210 at the front end. During machining, the coolant flows to the cutting edge 210 through the space formed between the inner surface of the groove 113 and the inner surface of the machining hole. Then, the coolant, together with the chips generated during machining, is discharged outside the machining hole through the aforementioned discharge groove 111.

[0043] Regarding the specific shape of the discharge groove 111, please refer to Figure 5 To illustrate. As shown in the figure, the discharge groove 111 has a straight section G1, a curved section G2, and a straight section G3.

[0044] The straight section G1 is the frontmost part of the discharge groove 111. A recess for mounting the cutting insert 200 is formed on the inner surface of the straight section G1. The straight section G1 extends in a straight line from the position of the cutting insert 200 toward the base end side along the rotation center axis AX.

[0045] The curved portion G2 is a portion that extends further towards the base end side from the end of the straight portion G1. In the curved portion G2, the discharge groove 111 bends and extends towards the opposite side of the rotation direction as it gets closer to the base end side from the front end side.

[0046] The straight section G3 is the portion that extends further towards the base end from the end of the curved section G2. Like the straight section G1, the straight section G3 extends as a whole along the rotation center axis AX.

[0047] Furthermore, the cross-sectional shape of the discharge groove 111 when cutting perpendicularly relative to the rotation center axis AX is approximately the same in the straight section G1, the curved section G2, and the straight section G3, respectively. In any part, the two slightly planar inner surfaces 111A and 111B of the discharge groove 111 form a certain angle. Inner surface 111A is the inner surface on which the cutting blade 200 is mounted, and inner surface 111B is the other inner surface.

[0048] As described above, in this embodiment, the discharge groove 111 is not a straight line overall, but rather a shape in which a portion (the curved portion G2) extends in a curved manner. Before explaining the advantages of the discharge groove 111 having such a shape, the structure of the comparative example will be described first. In this comparative example, the curved portion G2 as in this embodiment is not provided, and the discharge groove 111 extends in a straight line along the rotation center axis AX. Figure 6 This is a schematic diagram depicting the cut portion 110 of the main body 100 of the comparative example as viewed from its front side.

[0049] During the machining process, as described above, the main body 100 rotates around the rotation center axis AX. At this time, the cutting edge 210 is subjected to a force from the material being cut. Figure 6 Arrow AR1 indicates the force exerted on the cutting edge 210. The direction of this force is opposite to the direction on which the discharge groove 111 is formed, i.e., towards the guide pad 300.

[0050] The force indicated by arrow AR1 causes the front end of the body 100 to displace towards the side indicated by arrow AR1. However, this force causes the guide pad 300 to abut and press against the inner surface of the machined hole, thus the guide pad 300 experiences a reaction force. This applied reaction force is directed in the opposite direction to the force exerted on the cutting edge 210 (arrow AR1). As a result, displacement of the front end of the body 100 is suppressed, thus ensuring the straightness and roundness of the machined hole.

[0051] exist Figure 7 In (A), the forces applied to the body 100 are schematically depicted. In the same figure, the left side is the front end side and the right side is the rear end side. Arrow AR11 indicates the force exerted on the cutting edge 210. Arrow AR12 indicates the force exerted on the guide pad 300 from the inner surface of the machined hole. As mentioned above, the directions of these applied forces are opposite to each other.

[0052] However, these two forces are applied to different locations along the longitudinal direction of the body. Therefore, the forces do not cancel each other out to zero. Figure 7 Point P1 in (A) is the point on the front end side of the outer peripheral surface of the guide pad 300. The forces indicated by arrow AR11 and arrow AR12 are in opposite directions, resulting in a bending moment applied to the body 100, causing it to rotate about point P1 in the direction of arrow AR13. This applied bending moment is a force that displaces the longitudinal center of the body 100 in the direction of arrow AR14. Thus, as Figure 7 As exaggeratedly depicted in (B), the main body 100 bends into an arc shape during processing.

[0053] The force (arrow AR14) that causes the main body 100 to flex in this way is a force directed towards the opposite side of the side where the guide pad 300 is located. Figure 6 In the diagram, this force is represented by arrow AR2. The direction of this force is towards the direction in which the discharge groove 111 is formed. The direction of arrow AR2 is towards the part of the main body 100 where the meat is cut, which can be described as the bending direction in which the second moment of the cross section of the discharge groove 111 decreases as it forms.

[0054] That is, in this comparative example, the direction in which the longitudinal central portion of the main body 100 tends to displace due to the aforementioned bending moment is consistent with the bending direction in which the secondary moment of the forming section of the discharge groove 111 decreases. Therefore, the central portion of the main body 100 is prone to significant displacement due to the aforementioned bending moment. Due to this displacement, a portion of the main body 100 comes into contact with the inner surface of the machined hole, potentially reducing machining accuracy.

[0055] Therefore, in the main body 100 of this embodiment, by bending a portion (bent portion G2) of the discharge groove 111, the displacement of the central portion caused by the bending moment is suppressed.

[0056] exist Figure 8 In the middle, used with Figure 6 Similarly, the cutting portion 110 of the main body 100 of this embodiment is schematically depicted. Figure 8 In the diagram, arrow AR1 represents the force borne by the cutting edge 210, and arrow AR2 represents the force that causes the main body 100 to flex due to the bending moment.

[0057] exist Figure 8 When viewing the portion on the side of arrow AR2 from the rotation center axis AX, it can be seen that in this embodiment, this portion is not entirely removed to form the discharge groove 111, but rather a curved portion G is overlapped there. That is, when viewed along the rotation center axis AX, the force (arrow AR2) that causes the main body 100 to flex is applied within the angular range from the inner surface 111B of the straight portion G1 to the inner surface 111B of the straight portion G3.

[0058] In this embodiment, a bending portion G2 is provided in the discharge groove 111. As a result, the direction in which the longitudinal central portion of the main body wants to shift due to the bending moment during processing is different from the bending direction in which the secondary moment of the cross-section of the discharge groove 111 decreases as it forms. Therefore, compared with the past, the deflection of the main body 100 during processing can be suppressed.

[0059] Here, as Figure 8 As shown, when viewed from the front end along the rotation center axis AX, the angle between the inner surface 111B of the straight section G1 and the inner surface 111B of the straight section G3 is defined as the "torsion angle". The torsion angle can also be described as the change in the angle of the inner surface of the discharge groove when the position is changed from the front end to the base end.

[0060] Figure 9 This indicates the relationship between the torsion angle (horizontal axis) and the displacement of the central part of the main body 100 during machining (vertical axis). The "TH" in the same figure represents the upper limit of the displacement that can be tolerated for high-precision machining.

[0061] like Figure 9 As shown, if the torsion angle is below 40 degrees, the displacement of the central part will be within the upper limit TH. However, when the torsion angle exceeds 40 degrees, the displacement will increase sharply and exceed the upper limit TH.

[0062] Therefore, when forming the discharge groove 111 on the main body 100, it is preferable to keep the torsion angle within 40 degrees.

[0063] In this embodiment, the discharge groove 111 is made to be slightly straight overall, but only a portion of the discharge groove 111 is bent. Alternatively, for example, the portion of the discharge groove 111 near the base end (relative to the portion near the cutting blade 200 or the guide pad 300) can be bent entirely.

[0064] In this embodiment, since only one discharge trough 111 is formed, all the coolant needs to be discharged using only one discharge trough 111. Therefore, as Figure 8 As shown, the discharge groove 111 is formed into a relatively large groove. Specifically, in the cross-section of the main body 100 near the base end (relative to the portion near the first mounting portion 101 and the second mounting portion 102) when cut perpendicularly to the rotation center axis AX, the proportion of the discharge groove 111 is 20% or more. Furthermore, the aforementioned "proportion" refers to the proportion of the cross-sectional area of ​​the discharge groove 111 relative to the cross-sectional area (i.e., the area of ​​a circle) of the main body 100 without the discharge groove 111. In structures where the proportion is 20% or more, as in this embodiment, the effect of the bending of the discharge groove 111 becomes particularly significant.

[0065] Furthermore, the aforementioned proportion is more preferably 30% or more. However, in any case, to ensure the rigidity of the main body 100, the aforementioned proportion is preferably 40% or less.

[0066] The present embodiment has been described above with reference to specific embodiments. However, this disclosure is not limited to these specific embodiments. Even if those skilled in the art make appropriate design changes to these specific embodiments, as long as they possess the features of this disclosure, they are included within the scope of this disclosure. The elements, their configurations, conditions, shapes, etc., included in the above-described specific embodiments are not limited to those illustrated and can be appropriately modified. Regarding the elements included in the above-described specific embodiments, the combination can be appropriately changed as long as no technical contradiction is caused.

Claims

1. A body for use with drill bits, characterized in that, include: The first mounting part, located on the front end side, is the part for mounting the cutting edge; The second mounting part, located circumferentially on the front side at a different position than the first mounting part, is the part for mounting the guide pad. A discharge groove is formed on the outer peripheral surface, which extends from the front end side to the base end side, and is used to guide fluid towards the base end side and discharge it. At least a portion of the discharge groove bends towards the opposite side of the rotation direction as it gets closer to the base side from the front end side; The discharge channel has a first straight portion, a curved portion, and a second straight portion. The first straight portion is the frontmost part of the discharge channel. The curved portion is the portion that extends further from the base end of the first straight portion toward the base end. The second straight portion is the portion that extends further from the base end of the curved portion toward the base end. When viewed along the rotation center axis, as the position changes from the front end to the base end, the angle change of the inner surface of the discharge groove is within 40 degrees. The angle change is the angle between the inner surface of the first straight section and the inner surface of the second straight section.

2. The body according to claim 1, wherein, In the cross-section of the portion near the base end that is cut perpendicularly to the rotation center axis relative to the portion near the first mounting portion and the second mounting portion, the proportion of the discharge groove is more than 20%, and the proportion is the ratio of the cross-sectional area of ​​the discharge groove to the cross-sectional area of ​​the main body without the discharge groove.

3. The body according to claim 1, wherein, The second mounting part is arranged in a circumferential manner in multiple ways.

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