Multi-group drill bit with sharpened flank face

Abstract

The utility model relates to the technical field of drilling tools, in particular to a gang drill bit with a sharpened rear cutter face. The gang drill bit with the back cutter face sharpening comprises a handle body and a drill body which are integrally connected, crescent grooves are formed in a main cutting edge of a cutting part of the drill body, the pair of crescent grooves are symmetrically distributed along the axis of the drill body, and an outer edge, an arc edge and an inner edge are sequentially formed on the main cutting edge in the direction from the outer side to the inner side of the drill body. A chip groove is formed in the side wall of the drill body, an arc groove is formed in the rear tool face of the drill body, the distance value from the vertex angle tip of the inner edge to the starting point of the arc groove in the vertical direction is defined as L, and when the diameter of the drill body is smaller than or equal to 6 mm, the distance value L is 1.05 times of the diameter of the drill body; when the diameter of the drill body is larger than 6 mm, the distance value L is 1.35 times of the diameter of the drill body. According to the gang drill bit with the sharpened rear tool face, the swing of the drill bit during cutting machining is reduced, the hole wall smoothness and the machining precision of a drilled hole are improved, and the service life of the gang drill bit is further prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of drilling tools, in particular to a group drill bit with a back cutting edge sharpened. Background Art

[0002] The twist drill is a double-slot hole processing tool, named for its spiral appearance. Standard twist drills usually include a drill shank and a drill body structure, suitable for drilling operations in materials such as metal, plastic and wood. Among them, the cutting part of the drill body is composed of a main cutting edge, a secondary cutting edge and a chisel edge. However, in actual use, the cutting efficiency of the standard twist drill is low because its cutting edge is operated by push cutting. In addition, in the absence of pre-drilled positioning holes in the workpiece, the standard twist drill is prone to deviate from the predetermined drilling position when drilling and lacks center positioning capability.

[0003] In order to solve the defects of standard twist drills during use, the prior art has made improvements on the basis of standard twist drills and proposed a group drill bit structure. The group drill bit is an improved version of the standard twist drill. The structure of the group drill is a drill core tip, two side tips, two inner blades, an arc blade, an outer blade and a transverse blade, thus forming a three-point seven-blade drill type. For example, Chinese patent document CN204108413U discloses a seven-blade drill bit. The seven-blade drill bit uses the drill core tip and two symmetrical side tips on the left and right to quickly form a stable three-point centering. The drill bit is not easy to deviate in the axial direction, which improves the drilling accuracy and durability of the drill bit.

[0004] Although the cluster drill bit structure improves the center positioning ability of the standard twist drill to a certain extent, the cluster drill bit has swings during high-speed cutting (drill speed above 1800r / min), and the cluster drill bit lacks stability, which affects the finish and processing accuracy of the hole wall. In addition, the seven-edge structure of the cluster drill bit is prone to inconsistent wear, which leads to deviations in the cutting load of each cutting edge, thus affecting the drilling quality and the service life of the cluster drill bit. Summary of the invention

[0005] The technical problem to be solved by the utility model is how to provide a sharpening structure in the process of drilling holes with a group drill bit to reduce the swing of the drill bit during cutting, improve the smoothness of the hole wall and the processing accuracy of the drilled hole, and further extend the service life of the group drill bit.

[0006] In order to solve the above technical problems, the utility model proposes the following solutions:

[0007] A group drill bit with flank face grinding comprises a handle body and a drill body connected in one piece, a crescent groove is arranged on the main cutting edge of the cutting portion of the drill body, a pair of crescent grooves are symmetrically arranged along the axis of the drill body, an outer edge, a circular arc edge and an inner edge are sequentially formed on the main cutting edge along the direction from the outside to the inside of the drill body, a chip groove is arranged on the side wall of the drill body, the groove surface of the chip groove is the rake face, and the end face of the drill body is the flank face;

[0008] The back face of the drill body is provided with a sharpening structure, the sharpening structure includes an arc groove, a main cutting edge is formed at the intersection of one side of the front face and the back face, a back edge is formed at the intersection of the other side of the front face and the back face, the arc groove is located on the back edge, and a vertical distance value from the top angle tip of the inner edge to the starting point of the arc groove is defined as L;

[0009] When the diameter of the drill body is less than or equal to 6 mm, the distance value L is 1.05 times the diameter of the drill body;

[0010] When the diameter of the drill body is greater than 6 mm, the distance value L is 1.35 times the diameter of the drill body.

[0011] The utility model provides a group drill bit with a back-ground cutting edge, which, when in use, utilizes two side tips symmetrically arranged along the axis of the drill body to assist the drill core tip in contacting the surface of the workpiece being drilled, thereby helping to maintain the stability of the drill body and reducing the radial deviation of the drill bit during the drilling process. As the drilling process advances, the two inner cutting edges and the arc cutting edge begin to cut into the material, further expanding the diameter of the drill hole and beginning to form a hole wall. The arc cutting edge is conducive to forming a smooth hole wall, and the outer cutting edge is used to remove more material and ensure the processing size, which is conducive to optimizing the formation of chips and facilitating smooth chip removal.

[0012] During the drilling process, the grinding structure on the back face of the drill body is used to further help the chips to be discharged smoothly. The arc groove on the back edge reduces the friction between the contact surface between the drill body and the workpiece, further reduces the cutting resistance, improves the cutting speed and drilling efficiency, reduces the burrs generated during processing, and is conducive to forming a more precise and smooth hole wall surface. The grinding starting point of the arc groove is related to the diameter of the drill body and is suitable for the back face grinding of drills of different structural sizes.

[0013] The utility model provides a group drill bit with a ground back cutting edge, which has the following substantial characteristics and progress compared with the prior art: the group drill bit with a ground back cutting edge forms an arc groove on the back cutting edge by using an arc grinding method, which is beneficial to further help the chips to be discharged smoothly, so that the cutting part of the drill body remains sharp, greatly reducing the swing of the drill bit during cutting processing, reducing the wear of the main cutting edge, and extending the service life of the group drill bit. In addition, the design of the arc groove reduces the cutting resistance, improves the cutting speed and drilling efficiency, and improves the smoothness of the hole wall and the processing accuracy of the drilled hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of a group drill bit with flank sharpening in an embodiment of the utility model.

[0015] Figure 2 yes Figure 1 Schematic diagram of the top view structure.

[0016] Figure 3 It is a marked schematic diagram of a group drill bit with flank sharpening in an embodiment of the utility model.

[0017] Figure numerals: 1, drill body; 2, main cutting edge; 3, crescent groove; 4, chip groove; 5, back cutting surface; 6, arc groove; 7, top angle tip; 8, side tip; 9, transverse edge; 21, outer edge; 22, arc edge; 23, inner edge. DETAILED DESCRIPTION

[0018] The specific implementation of the utility model is described in detail below with reference to the accompanying drawings.

[0019] like Figure 1-Figure 3 As shown, in the embodiment of the utility model, a group drill bit with back cutting edge grinding is proposed, which aims to reduce the swing of the drill bit during cutting processing, improve the smoothness of the hole wall and the processing accuracy of the drilled hole, and further extend the service life of the group drill bit.

[0020] A group drill bit with a flank sharpening proposed in the embodiment of the utility model forms an arc groove 6 on the flank surface 5 by means of arc grinding, which is beneficial to further help the chips to be discharged smoothly, so that the cutting part of the drill body 1 remains sharp, greatly reducing the swing of the drill bit during cutting processing, reducing the wear of the main cutting edge 2, and extending the service life of the group drill bit. In addition, the design of the arc groove 6 reduces the cutting resistance, improves the cutting speed and drilling efficiency, and improves the smoothness of the hole wall and the processing accuracy of the drilled hole.

[0021] like Figure 1 As shown, a group drill bit with flank sharpening includes a handle body and a drill body 1 connected in one piece. A crescent groove 3 is provided on the main cutting edge 2 of the cutting portion of the drill body 1. A pair of crescent grooves 3 are symmetrically arranged along the axis of the drill body 1. For example, the handle body is cylindrical, and a clamping portion is provided on the side wall of the cylindrical handle body.

[0022] like Figure 1 Combination Figure 2 As shown, the main cutting edge 2 is formed with an outer edge 21, a circular edge 22 and an inner edge 23 in sequence from the outer side to the inner side of the drill body 1. A chip groove 4 is provided on the side wall of the drill body 1. The groove surface of the chip groove 4 is the rake face. The end face of the drill body 1 is the flank face 5.

[0023] like Figure 1 Combination Figure 3 As shown, a sharpening structure is provided on the flank face 5 of the drill body 1. The sharpening structure includes an arc groove 6. The main cutting edge 2 is formed at the intersection of one side of the rake face and the flank face 5. The rear edge is formed at the intersection of the other side of the rake face and the flank face 5. The arc groove 6 is located on the rear edge. The vertical distance value from the top angle tip 7 of the inner blade 23 to the starting point of the arc groove 6 is defined as L.

[0024] In order to be suitable for the grinding of the back cutting edge 5 of drill bits of different structural sizes, the grinding starting point position of the arc groove 6 is related to the diameter of the drill body 1. When the diameter of the drill body 1 is less than or equal to 6 mm, the distance value L is 1.05 times the diameter of the drill body 1; when the diameter of the drill body 1 is greater than 6 mm, the distance value L is 1.35 times the diameter of the drill body 1.

[0025] In order to make the arc groove 6 more suitable for group drill bits of different structural sizes, the radius of the arc groove 6 is also related to the diameter of the drill body 1. The radius of the arc groove 6 is r, and the diameter of the drill body 1 starts from 3 mm, r is 1 mm, and r increases by 0.25 mm for every 0.8 mm increase in the diameter of the drill body 1.

[0026] like Figure 2 As shown, a chisel edge 9 is provided between a pair of inner edges 23. The included angle formed by the chisel edge 9 and the main cutting edge 2 is 55 o -60 o The chisel edge 9 is used to complete the plane machining of the hole bottom and to break the chips. For example, the length of the chisel edge 9 is 5%-10% of the diameter of the drill body 1.

[0027] The arc blade 22 is used to further expand the diameter of the drill hole and help form the hole wall. The arc blade 22 is conducive to forming a smooth hole wall. For example, the radius of the arc blade 22 is 12%-18% of the diameter of the drill body 1.

[0028] like Figure 3 As shown, a side tip 8 is provided between the outer blade 21 and the circular arc blade 22. The vertical distance between the top angle tip 7 of the inner blade 23 and the side tip 8 in the diameter direction of the drill body 1 is a, and the ratio of the distance value a to the diameter of the drill body 1 is 0.3-0.4. The vertical distance between the top angle tip 7 of the inner blade 23 and the side tip 8 in the axial direction of the drill body 1 is b, and the ratio of the distance value b to the diameter of the drill body 1 is 0.08-0.13. In this way, the position of the side tip 8 on the main cutting edge 2 is conveniently determined by the distance values ​​a and b, which is beneficial to provide auxiliary positioning for the grinding of the crescent groove 3, and further reduces the difficulty of grinding the circular arc blade 22.

[0029] When a group drill bit with back face grinding proposed in the embodiment of the utility model is used, Figure 1As shown, two side tips 8 arranged symmetrically along the axis of the drill body 1 and the auxiliary drill core tip contact the surface of the drilled workpiece together, which helps to maintain the stability of the drill body 1 and reduce the radial deviation of the drill bit during the drilling process. As the drilling process progresses, the two inner blades 23 and the arc blade 22 begin to cut into the material, further expanding the diameter of the drill hole and starting to form the hole wall. The arc blade 22 is conducive to forming a smooth hole wall. The outer blade 21 is used to remove more material and ensure the processing size, which is conducive to optimizing the formation of chips and facilitating smooth chip removal.

[0030] During the drilling process, the grinding structure on the rear cutting edge 5 of the drill body 1 is used to further help the chips to be discharged smoothly. The arc groove 6 located on the rear edge reduces the friction between the contact surface of the drill body 1 and the workpiece, further reduces the cutting resistance, improves the cutting speed and drilling efficiency, reduces the burrs generated during processing, and is conducive to forming a more precise and smooth hole wall surface.

[0031] In order to more intuitively reflect the performance improvement of a group drill bit with back face grinding proposed in the embodiment of the utility model, a comparative experiment was conducted on the time required to complete the same drilling task of the group drill bit and two other ordinary group drill bits on the market without arc groove grinding structure. Among them, the three group drill bits participating in the experiment were driven by the same bench drill (Xi Ling bench drill), and blind holes were drilled on steel plates of the same material and size, and the drilling time of each drill bit was recorded respectively.

[0032] The experiment selected 304 stainless steel plates as the drilling objects, the drilling speed was set to 1360r / min, and the depth of the blind hole was 10mm. The diameters of the three group drill bits are all 3mm. The test results are as follows: The processing time of the three group drill bits increased with the progress of the experiment. Two ordinary group drills on the market without arc groove grinding structures could not continue to complete the drilling operation after drilling 87 and 84 blind holes, respectively. A group drill bit with a back blade grinding proposed in the embodiment of the utility model can continue to drill after drilling 169 blind holes.

[0033] It can be seen from the above test results that the back-face sharpened group drill bit proposed in the embodiment of the utility model has a longer service life than the ordinary group drill bit in the prior art. The design of the arc groove keeps the cutting part of the drill body sharp, greatly reduces the swing of the drill bit during cutting, reduces the wear of the main cutting edge, prolongs the service life of the group drill bit, and reduces the cutting resistance, improves the cutting speed and drilling efficiency, and improves the hole wall finish and processing accuracy of the drilled hole.

Claims

1. A group drill bit with flank face grinding, comprising a handle body and a drill body connected in one piece, a crescent groove is arranged on the main cutting edge of the cutting portion of the drill body, a pair of crescent grooves are symmetrically arranged along the axis of the drill body, an outer blade, a circular arc blade and an inner blade are formed on the main cutting edge in sequence from the outside to the inside of the drill body, a chip groove is arranged on the side wall of the drill body, the groove surface of the chip groove is a rake face, and the end face of the drill body is a flank face, characterized in that: The back face of the drill body is provided with a sharpening structure, the sharpening structure includes an arc groove, a main cutting edge is formed at the intersection of one side of the front face and the back face, a back edge is formed at the intersection of the other side of the front face and the back face, the arc groove is located on the back edge, and a vertical distance value from the top angle tip of the inner edge to the starting point of the arc groove is defined as L; When the diameter of the drill body is less than or equal to 6 mm, the distance value L is 1.05 times the diameter of the drill body; When the diameter of the drill body is greater than 6 mm, the distance value L is 1.35 times the diameter of the drill body.

2. The flank-grinding group drill bit according to claim 1, characterized in that: The radius of the arc groove is r, the diameter of the drill body starts from 3 mm, r is 1 mm, and r increases by 0.25 mm for every 0.8 mm increase in the diameter of the drill body.

3. The flank-grinding group drill bit according to claim 1, characterized in that: A chisel edge is provided between the pair of inner edges, and the angle formed between the chisel edge and the main cutting edge is 55 o -60 o .

4. The flank-grinding group drill bit according to claim 3, characterized in that: The length of the chisel edge is 5%-10% of the diameter of the drill body.

5. The flank-grinding group drill bit according to claim 1, characterized in that: The radius of the circular arc cutting edge is 12%-18% of the diameter of the drill body.

6. The flank-grinding group drill bit according to claim 1, characterized in that: The handle body is cylindrical, and a clamping portion is arranged on the side wall of the cylindrical handle body.

7. The flank-grinding group drill bit according to claim 1, characterized in that: A side tip is provided between the outer blade and the arc blade, a vertical distance between the top angle tip of the inner blade and the side tip in the diameter direction of the drill body is a, and a ratio of the distance value a to the diameter of the drill body is 0.3-0.

4.

8. The flank-ground group drill bit according to claim 7, characterized in that: The vertical distance between the top angle tip and the side tip of the inner blade in the axial direction of the drill body is b, and the ratio of the distance value b to the diameter of the drill body is 0.08-0.13.

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