CN101912987B - Drill bit for processing deep hole with large length-diameter ratio - Google Patents

Abstract

The invention discloses a drill bit for processing deep holes with a large length-to-diameter ratio, which comprises a drill body. The chip flute and the secondary cutting edge extending from the shank, the drill point is provided with a rake face, a relief face and a chisel edge, the rake face and the relief face intersect to form a main cutting edge, and the main cutting edge It is formed by connecting a straight line inner edge and a curved outer edge, and the straight line inner edge is connected with a chisel edge. The cutting edge and the arc transition edge protrude toward the inside of the chip flute, the arc cutting edge is connected with the secondary cutting edge, and the arc transition edge is connected with the straight inner edge. The drill bit for machining deep holes with a large length-to-diameter ratio has the advantages of simple structure, good durability, strong chip breaking and chip removal capabilities, and high cutting efficiency.

Description

Drill bits for deep hole machining with large length-to-diameter ratio

technical field

The invention relates to metal cutting technology, in particular to a drill bit for deep hole processing with a large length-to-diameter ratio.

Background technique

There are many types of cutting tools for deep hole machining. At present, extra-long twist drills, gun drills, BTA drills and self-guided jet drills are commonly used. They have certain shortcomings in manufacturing and use, such as the difficulty of chip removal for extra-long twist drills. During the drilling process, after drilling 2 to 3 times the depth of the hole, it is necessary to frequently lift the tool to remove chips. The lubrication and cooling conditions of the cutting edge are poor, the cutting temperature is high, the service life of the drill bit is low, the rigidity of the drill bit is poor, and it is easy to cause self-excited vibration. Gun drills, BTA deep hole drills and self-guided jet drills require cemented carbide as the blade in manufacturing, and it is difficult to weld the blade and the cutter body, and a special hydraulic seal pressure supply system is required for use, and the production cost is too high .

The patent document with the notification number CN2036077U discloses a deep-hole twist drill. The helical flute of the drill bit is formed by rotating a parabola and an arc. Tapered thick drill core, the drill point is corrected by cross grinding method. It does not require special machine tools and tooling when used, and can be used on ordinary bench drills, vertical drills, lathes, and boring machines, and the chips formed are in the shape of ribbons. However, when the deep hole drill is working, because the processing hole is deep and the processing condition is bad, if the drill has no edge back, the tool will have a problem of poor guidance. The type determines that when the tool cuts metal materials with good ductility, the ribbon chips will be longer and difficult to break, making the chip flute easy to be blocked by chips, making it difficult for cutting fluid to flow in, thus affecting the cooling of the cutting place and reducing Drilling efficiency and drill life. the

The patent document with the notification number CN2806004Y discloses a twist drill bit, which includes a cutter body and a cutter head. There is a spiral groove on the cutter body. At the end of the spiral groove, the cutting part of the cutter head includes two Symmetrical cutting edges, two symmetrical secondary cutting edges, the two symmetrical cutting edges are connected by drill cores, the central part of the two connected cutting edges is S-shaped, and the two sides are straight lines respectively. The cutting edge is a chamfered edge. Though the drill bit of the invention has better centering performance than the standard drill bit, its drill point is not convenient for grinding, and the manufacturing difficulty is large and the manufacturing cost is high.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and provide a drill bit for deep hole machining with a large length-to-diameter ratio, which has a simple structure, good durability, strong chip breaking and chip removal capabilities, and high cutting efficiency.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A drill for machining deep holes with a large length-to-diameter ratio, comprising a drill body, the drill body includes a drill tip, a chip removal part and a shank, and the chip removal part is provided with a shank extending from the drill tip to the shank The chip flute and the secondary cutting edge, the drill point is provided with a rake surface, a relief surface and a chisel edge, the rake surface and the relief surface intersect to form a main cutting edge, and the main cutting edge is composed of a straight inner edge The curved outer edge is connected with the curved outer edge, and the straight inner edge is connected with the chisel edge. The curved outer edge includes a circular arc cutting edge, a straight line cutting edge and a circular arc transition edge connected sequentially from the outside to the inside. The circular arc cutting edge and the The arc transition edge protrudes toward the inside of the chip flute, the arc cutting edge is connected with the secondary cutting edge, and the arc transition edge is connected with the straight inner edge.

The rake angles of the straight inner edge and the arc transition edge are zero or negative, the radial rake angle of the arc cutting edge is negative, and the rake angle of the straight cutting edge is positive.

Both the straight inner edge and the straight cutting edge are tangent to the arc transition edge, the angle θ between the straight inner edge and the straight cutting edge is 18° to 38°, and the radius r of the arc transition edge is 0.5mm ~3.5mm.

There are two main cutting edges, and the two main cutting edges are arranged symmetrically to the center. The straight cutting edges in the two main cutting edges are parallel to each other, and the distance S between the two straight cutting edges is equal to the core thickness K of the drill bit. 0.55 to 0.75 times, the core thickness K of the drill bit is 0.2 to 0.4 times the diameter D of the drill tip.

The chord length L of the arc cutting edge is 0.08-0.28 times the radius R of the drill tip.

The relief surface is composed of a first rear face, a second rear face and a third rear face with increasing angles in sequence.

Compared with the prior art, the present invention has the advantages of:

The drill bit used for deep hole processing with a large length-to-diameter ratio of the present invention has a curved outer edge comprising an arc cutting edge, a straight cutting edge and an arc transition edge sequentially connected from the outside to the inside, and the arc cutting edge and the arc transition edge face toward the The protrusion inside the chip flute improves the strength of the tool tip and enhances the heat dissipation effect. While ensuring the good centering of the tool, it can avoid high stress concentration points on the raised curve during cutting, reducing the main cutting edge especially The load per unit length of the curved outer edge improves tool durability and cutting performance. The radial rake angle of the arc cutting edge is negative, and the chips curl and flow to the hole wall at the arc cutting edge; the rake angle of the straight cutting edge is positive, and the chips curl and flow to the chip flute at the straight cutting edge; When the rake angle changes from the arc transition edge to the straight inner edge and becomes zero or negative, the chips will curl and flow to the feed direction of the tool. From the perspective of the chip flow direction on the entire main cutting edge, the middle part of the chip (at the straight cutting edge) The direction of the force is opposite to that of the two ends (the arc cutting edge and the straight inner edge), so that the arc transition edge becomes the junction of the opposite flow of chips, and the chips are twisted and broken here to form a chip unit. The arc transition edge The presence of the chip not only enhances the strength here, but also solves the disadvantages of not being easy to break chips here, so that the chip unit forms a conical shape similar to a tadpole, and the chip shape is similar to a conical tadpole shape. , the narrow end is the breaking part of the chip, and the chip has a slender tail-shaped extension after the narrow end. The structure of this chip unit is the most ideal chip structure in deep hole machining with large length-to-diameter ratio, and it is very easy to discharge. , will not form blockage in the hole, does not need to lift the tool to remove chips, greatly improves the working efficiency of deep hole processing with large aspect ratio, and makes the drill bit used for deep hole processing with large aspect ratio according to the present invention feed the long diameter at one time The ratio can reach more than 15. Reasonably setting the distance between two parallel straight cutting edges can reduce the cutting force and torque of the drill bit during deep hole drilling, and reduce the chance of the drill bit breaking. The arc cutting edge must be set within a certain range. If the width of the raised arc cutting edge is too large, the chips will flow to the hole wall and may scratch the hole wall, reducing the surface quality of the hole; if the raised If the arc cutting edge is too small, the purpose of improving the tool strength and heat dissipation effect cannot be achieved. Experiments have proved that when the chord length L of the arc cutting edge is 0.08 to 0.28 times the radius R of the drill tip, it has the best comprehensive effect. The drill bit for deep hole machining with large length-to-diameter ratio of the present invention is based on the above-mentioned structural features, so that the thickness distribution of chips along the main cutting edge is relatively uniform, the chip breaking effect is good, the chip deformation is small, and the chips can pass through the chip flute smoothly. Therefore, the present invention is particularly suitable for drilling steel, stainless steel, cast iron and aluminum alloy materials with a hardness below 48HRC.

Description of drawings

Fig. 1 is the front view structure schematic diagram of the present invention;

Fig. 2 is the end view enlarged structure schematic diagram of drill tip portion of the present invention;

Fig. 3 is a schematic diagram of the enlarged structure of the main cutting edge part in Fig. 2;

Fig. 4 is the schematic diagram of the three-dimensional structure of the drill point in the present invention;

Fig. 5 is a schematic diagram of the radial rake angle of the arc cutting edge in the present invention;

Fig. 6 is a schematic diagram of the rake angle of a straight cutting edge in the present invention;

Fig. 7 is a schematic diagram of the rake angle of the arc transition edge in the present invention;

Fig. 8 is a schematic view of the rake angle of the straight inner blade in the present invention.

Each label in the figure means:

1. Drill bit body; 2. Drill point; 3. Chip removal part; 4. Shank; 5. Main cutting edge; 31. Chip flute; 32. Secondary cutting edge; 21. Rake face; 23, chisel edge; 51, straight inner edge; 52, curved outer edge; 221, first back; 222, second back; 223, third back; 521, arc transition edge; 522, straight cutting edge; 523, arc cutting edge.

Detailed ways

Figures 1 to 8 show an embodiment of a drill bit for deep hole machining with a large aspect ratio according to the present invention. The drill bit includes a drill body 1, and the drill body 1 includes a drill tip part 2, a chip removal part 3 and a shank. 4. The chip removal part 3 is provided with a chip removal flute 31 and a secondary cutting edge 32 extending from the drill tip 2 to the shank 4, and the drill tip 2 is provided with a rake face 21, a relief face 22 and a chisel edge 23. The clearance surface 22 is composed of a first back face 221, a second back face 222, and a third back face 223 whose angles increase sequentially. It is connected with the curved outer edge 52, and the straight inner edge 51 is connected with the chisel edge 23. The curved outer edge 52 includes a circular arc cutting edge 523, a straight line cutting edge 522 and a circular arc transition edge 521, which are sequentially connected from outside to inside. The edge 523 and the arc transition edge 521 protrude towards the inside of the chip flute 31, the arc cutting edge 523 is connected with the secondary cutting edge 32, and the arc transition edge 521 is connected with the straight inner edge 51. Strength, and enhanced heat dissipation effect, while ensuring good centering of the tool, it can avoid high stress concentration points on the raised curve during cutting, reduce the load on the main cutting edge 5, especially the curved outer edge 52 unit length, so that Tool durability and cutting performance are improved. The drill bit for deep hole machining with large length-to-diameter ratio of the present invention is based on the above-mentioned structural features, so that the thickness distribution of chips along the main cutting edge 5 is relatively uniform, the effect of chip breaking is good, and the deformation of chips is small, so that chips can pass smoothly through chip removal Groove 31 discharges, therefore, the present invention is particularly suitable for the drilling of steel, stainless steel, cast iron and aluminum alloy materials whose hardness is below 48HRC.

In this embodiment, the radial rake angle of the arc cutting edge 523 is α, the rake angle of the arc transition edge 521 is β, the rake angle of the straight cutting edge 522 is γ, and the rake angle of the straight inner edge 51 is δ, wherein The rake angles of the straight inner edge 51 and the arc transition edge 521 are zero or negative, the radial rake angle of the arc cutting edge 523 is negative, and the rake angle of the straight cutting edge 522 is positive, because the arc cutting edge 523 The radial rake angle is negative, and the chips at the arc cutting edge 523 curl and flow to the hole wall; because the rake angle of the straight cutting edge 522 is positive, the chips curl at the straight cutting edge 522 and flow into the chip flute 31; From the arc transition edge 521 to the straight inner edge 51, the rake angle changes to zero or a negative value, and the chips will curl and flow to the feed direction of the tool. From the perspective of the flow direction of the chips on the entire main cutting edge 5, the middle part of the chips (straight cutting edge 522) is opposite to the direction of force acting on both ends (arc cutting edge 523 and straight inner edge 51), so that the arc transition edge 521 becomes the junction of the opposite flow of chips, where the chips are twisted and broken to form Chip unit, the existence of the circular arc transition edge 521 not only enhances the strength here, but also solves the disadvantages that the chip is not easy to break here, so that the chip unit forms a conical shape similar to a tadpole, and the shape of the chip is similar to a conical tadpole. The wide mouth end of the unit has an everted edge, and the narrow mouth end is the broken part of the chip. After the narrow mouth end, the chip has a slender tail-shaped extension. The ideal chip structure, which is easy to discharge, will not form a blockage in the hole, and does not need to lift the tool to remove chips, which greatly improves the working efficiency of deep hole processing with large length-to-diameter ratio. In this embodiment, both the straight inner edge 51 and the straight cutting edge 522 are tangent to the arc transition edge 521, the angle θ between the straight inner edge 51 and the straight cutting edge 522 is 18°-38°, and the arc transition edge 521 The radius r is 0.5 mm to 3.5 mm. There are two cutting edges 5, and the two cutting edges 5 are arranged symmetrically to the center. The straight cutting edges 522 in the two cutting edges 5 are parallel to each other, and the distance S between the two straight cutting edges 522 is equal to the core thickness K of the drill bit. 0.55 to 0.75 times, the core thickness K of the drill bit is 0.2 to 0.4 times the diameter D of the drill tip 2 . Reasonably setting the distance between the two parallel straight cutting edges 522 can reduce the cutting force and torque of the drill bit during deep hole drilling, and reduce the probability of the drill bit breaking. The arc cutting edge 523 must be set within a certain range. If the width of the raised arc cutting edge 523 is too large, chips will flow to the hole wall, which may scratch the hole wall and reduce the surface quality of the hole; If the starting arc cutting edge 523 is too small, the effect of improving the tool strength and heat dissipation will not be obvious. Experiments have shown that when the chord length L of the arc cutting edge 523 is 0.08-0.28 times the radius R of the drill tip, it has the best comprehensive effect.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. A drill bit for machining deep holes with a large length-to-diameter ratio, comprising a drill body (1), and the drill body (1) includes a drill tip portion (2), a chip removal portion (3) and a shank portion (4) , the chip removal part (3) is provided with a chip removal flute (31) and a secondary cutting edge (32) extending from the drill tip (2) to the shank (4), and the drill tip (2) is provided with rake face (21), relief face (22) and chisel edge (23), the rake face (21) intersects with the relief face (22) to form the main cutting edge (5), the main cutting edge ( 5) It is formed by connecting a straight inner edge (51) and a curved outer edge (52), the straight inner edge (51) is connected with the chisel edge (23), and the feature is that the curved outer edge (52) includes a self- An arc cutting edge (523), a straight cutting edge (522) and an arc transition edge (521) connected in sequence from outside to inside, the arc cutting edge (523) and the arc transition edge (521) are both facing The inside of the flute (31) protrudes, the arc cutting edge (523) is connected to the secondary cutting edge (32), and the arc transition edge (521) is connected to the straight inner edge (51). 2. The drill bit for deep hole processing with large aspect ratio according to claim 1, characterized in that: the rake angles of the straight inner edge (51) and the arc transition edge (521) are zero or negative, The radial rake angle of the arc cutting edge (523) is negative, and the rake angle of the straight cutting edge (522) is positive. 3. The drill bit for deep hole processing with large length-to-diameter ratio according to claim 1 or 2, characterized in that: the straight inner edge (51) and the straight cutting edge (522) are both connected with the arc transition edge (521 ), the included angle θ between the straight inner edge (51) and the straight cutting edge (522) is 18°-38°, and the radius r of the arc transition edge (521) is 0.5mm-3.5mm. 4. The drill bit for deep hole processing with large length-to-diameter ratio according to claim 1 or 2, characterized in that: there are two main cutting edges (5), and the two main cutting edges (5) are centered Symmetrically arranged, the straight cutting edges (522) of the two main cutting edges (5) are parallel to each other, and the distance S between the two straight cutting edges (522) is 0.55 to 0.75 times the core thickness K of the drill bit. The core thickness K is 0.2 to 0.4 times the diameter D of the drill tip (2). 5. The drill bit for deep hole processing with large length-to-diameter ratio according to claim 3, characterized in that: there are two main cutting edges (5), and the two main cutting edges (5) are symmetrically arranged in the center , the straight cutting edges (522) of the two main cutting edges (5) are parallel to each other, the distance S between the two straight cutting edges (522) is 0.55 to 0.75 times the drill core thickness K, the drill core thickness The value K is 0.2 to 0.4 times the diameter D of the drill tip (2). 6. The drill bit for deep hole processing with large aspect ratio according to claim 1 or 2, characterized in that: the chord length L of the arc cutting edge (523) is the radius R of the drill tip (2) 0.08 to 0.28 times. 7. The drill bit for deep hole processing with large aspect ratio according to claim 5, characterized in that: the chord length L of the circular arc cutting edge (523) is 0.08~ 0.28 times. 8. The drill bit for deep hole processing with large length-to-diameter ratio according to claim 1 or 2, characterized in that: the relief surface (22) is sequentially increased from the first back surface (221), the second rear (222) and third rear (223). 9. The drill bit for deep hole processing with large length-to-diameter ratio according to claim 7, characterized in that: the relief surface (22) is sequentially increased from the first back surface (221), the second back surface ( 222) and the third rear (223).

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